Review of technical literature and trends
related to automobile mass- reduction technology
UCD- ITS- RR- 10- 10
May 2010
Prepared for:
California Air Resources Board
Prepared by:
Nicholas Lutsey
Institute of Transportation Studies
University of California, Davis
ii
Acknowledgements
This report is supported by a contract from the California Air Resources Board ( under Agreement
Number 08- 626). The statements and conclusions in this report are those of the researcher and not
necessarily those of the California Air Resources Board. The mention of commercial products, their
source, or their use in connection with material reported herein is not to be construed as an actual or
implied endorsement of such products.
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Table of contents
Acknowledgements ............................................................................................................................... .. ii Table of contents ............................................................................................................................... ..... iii Acronyms, abbreviations, units............................................................................................................... iv Lists of tables and figures ........................................................................................................................ v Executive summary........................................................................................................................ ........ vi 1. Introduction ............................................................................................................................... ....... 1 2. Background..................................................................................................................... .................. 1 3. Vehicle mass reduction: Survey of trends and technologies ............................................................. 6 3.1. General technology trends...................................................................................................... 7 3.2. The existing fleet of vehicle models ...................................................................................... 11 3.3. Emerging mass- reduction technology and automaker plans ............................................... 12 3.4. Advanced mass- optimized vehicle designs ........................................................................... 18 4. Implications ............................................................................................................................... ..... 33 4.1. Vehicle mass- reduction and policies for CO2 emissions and fuel economy......................... 34 4.2. Vehicle mass- reduction and electric drivetrain technology ................................................. 36 5. Conclusions ............................................................................................................................... ..... 38 References ............................................................................................................................... .............. 40
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Acronyms, abbreviations, units
AHSS: Advanced high- strength steel
Al: Aluminum
CAFE: Corporate Average Fuel Economy
CARB: California Air Resources Board
CO2: Carbon dioxide
gCO2/ mi: gram of carbon dioxide per mile
gallon: gallon, equal to 3.785 liters
HSS: High- strength steel
lb: pound, equal to 0.4535 kilogram
kg: kilogram, equal to 2.205 pounds
Mg: Magnesium
mi: Mile, equal to 1,609 meters
mpg: Miles per gallon
PNGV: Partnership for a New Generation of Vehicles
SMC: Sheet- molded composite
ton: U. S. ton, equal to 2,000 pounds
U. S. EPA: United States Environmental Protection Agency
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Lists of tables and figures
Tables:
Table 1. Vehicle mass breakdown by system and components .................................................................... 6 Table 2. Component weight- reduction potential from technologies on production vehicles ..................... 14 Table 3. Examples of overall vehicle weight reduction from production vehicles..................................... 16 Table 4. Automaker industry statements regarding plans for vehicle mass- reduction technology ............ 17 Table 5. Summary of Honda NS- X............................................................................................................. 18 Table 6. Summary of Ford P2000............................................................................................................... 19 Table 7. Summary of DaimlerChrysler ESX .............................................................................................. 19 Table 8. Summary of General Motors Precept ........................................................................................... 19 Table 9. Summary of Rocky Mountain Institute Revolution...................................................................... 20 Table 10. Summary of aluminum- intensive Audi space frame technology................................................ 20 Table 11. Summary of aluminum- intensive Jaguar XJ............................................................................... 21 Table 12. Summary of Porsche Engineering Advanced Concept Vehicle ................................................. 21 Table 13. Summary of Ford and U. S. Army IMPACT Ford F150 ............................................................. 22 Table 14. Summary of Auto/ Steel Partnership Future Generation Vehicle................................................ 22 Table 15. Summary of ThyssenKrupp New Steel Body............................................................................. 23 Table 16. Summary of DaimlerChrysler Dodge Durango Next Generation Frame project ....................... 23 Table 17. Summary of Advanced Materials Partnership magnesium- intensive vehicle project ................ 24 Table 18. Summary of IBIS and Aluminum Association aluminum- intensive vehicle.............................. 24 Table 19. Summary of Volkswagen- led European Super Light Car project .............................................. 25 Table 20. Summary of EDAG and WorldAutoSteel Future Steel Vehicle project..................................... 26 Table 21. Summary of Lotus Engineering Low and High Development vehicle project........................... 26 Table 22. Findings related to the costs of mass- reduced vehicle designs................................................... 33 Table 23. Worldwide automobile efficiency and GHG standards .............................................................. 34
Figures:
Figure 1. Light duty vehicle weight trends for model years 1975 to 2009 ( U. S. EPA, 2009a) .................... 2 Figure 2. U. S. light duty vehicle trends for weight, acceleration, fuel economy, and weight-adjusted
fuel economy for model years 1975- 2009 ( U. S. EPA, 2009a data)............................... 3 Figure 3. U. S. automobile weight and CO2 emissions.................................................................................. 4 Figure 4. Effect of mass- reduction technology on CO2 emission rate for constant performance................. 5 Figure 5. Distinction between fleet " downsizing" and vehicle " mass- reduction technology"...................... 5 Figure 6. Historical shift in vehicle composition by mass ( based on Taub et al, 2007) ............................... 7 Figure 7. Automotive material properties and approximate costs ( based on data from Caceres, 2007:
U. S. DOE, 2006; Powers, 2000; Lovins and Cramer, 2004; Stodolsky et al, 1995b).................. 9 Figure 8. Example of higher- strength, higher- cost materials achieving a net decrease in component
cost ( based on steel alloy options for B- pillar from Adam, 2009) ............................................... 9 Figure 9. Illustration of body- on- frame and unibody vehicle construction ................................................ 10 Figure 10. Model year 2008 U. S. light duty vehicle curb weight and size................................................. 11 Figure 11. Sales- weighted average vehicle weight and size for each automaker group............................. 12 Figure 12. Mass reduction from the body structure of mass- optimized vehicle designs............................ 28 Figure 13. Material composition of mass- optimized vehicle body designs................................................ 29 Figure 14. Vehicle body and overall vehicle mass impacts from mass- optimized designs........................ 29 Figure 15. Vehicle mass reduction and material composition of PNGV prototypes .................................. 30 Figure 16. Comparison of Lotus mass- reduced designs to historical vehicle composition trend............... 31 Figure 17. The mass by material of the Lotus baseline and mass- reduced vehicle designs ....................... 32 Figure 18. Impact of an identical efficiency- and- mass- reduction technology package in size- and
mass- indexed CO2 emission regulations .................................................................................... 35 Figure 19. CO2 emissions of model year 2008 hybrids and their non- hybrid counterparts........................ 37
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Executive summary
Past automotive trends, ongoing technology breakthroughs, and recent announcements by
automakers make it clear that reducing the mass of automobiles is a critical technology objective for
vehicle performance, carbon dioxide ( CO2) emissions, and fuel economy. Vehicle mass- reduction
technology offers the potential to reduce the mass of vehicles without compromise in other vehicle
attributes, like acceleration, size, cargo capacity, or structural integrity. As regulatory agencies continue
to assess more stringent CO2 and fuel economy standards for the future, it is unclear the exact extent to
which vehicle mass- reduction technology will be utilized alongside other efficiency technologies like
advanced combustion and hybrid system technology. This report reviews ongoing automotive trends,
research literature, and advanced concepts for vehicle mass optimization in an attempt to better
characterize where automobiles – and their mass in particular – might be headed.
Several findings on mass- reduction technology trends emerge from this assessment. Automakers
are deploying a wide variety of advanced materials in new vehicle models. The competition between
alternative materials like high- strength steel, aluminum, magnesium, and plastic continues to result in a
rich portfolio of options to reduce vehicle mass component- by- component ( e. g., engine, beams, panels,
etc). In addition, design approaches for the vehicle body structure that more heavily utilize higher-strength
steels and aluminum are beginning to be embraced by some manufacturing companies, and this
could substantially reduce the mass of vehicle models. Several major studies, as well as some automakers’
announced plans, indicate that mass- reduction technology with minimal additional manufacturing cost
could achieve up to a 20% reduction in the mass of new vehicles in the 2015- 2020 timeframe. This
incremental mass- reduction approach would, in turn, result in a 12% to 16% reduction in CO2 emissions
while maintaining constant vehicle size and performance.
Greater potential for future CO2 emission reductions involves the commercialization of more
advanced mass- optimization technologies that go beyond the near- term incremental approaches. Greater
reductions in vehicle mass result from more comprehensive vehicle optimization designs that incorporate
component- level mass reduction, a diverse mix of materials, secondary mass- reduction effects, new
manufacturing techniques, and component integration to systematically make the whole vehicle more
mass- efficient. These more advanced mass- optimization techniques could yield vehicle mass reductions
of 30% or greater but would involve some additional costs and manufacturing process modifications.
This scale of mass- reduction has been found to be feasible for introduction in model year 2020 vehicles.
Beyond its direct CO2 improvement, this scale of mass- reduction technology could involve powertrain
cost improvements that could help enable affordable hybrid electric- drive vehicles.
Based on automakers’ commitments to deploy mass- reduction technology, this study offers several
policy implications. Automakers and suppliers are moving forward with advanced mass- optimization
techniques apparently at a faster rate than regulators forecast or acknowledge. Several worldwide vehicle
efficiency policies are directly indexed to the mass of vehicles ( e. g., in Europe, China, and Japan), and
therefore these standards stand to provide a lesser incentive for automakers to pursue and deploy
emerging mass- reduction technologies in their new vehicle designs. Furthermore, U. S. regulators
similarly have downplayed the importance of mass- reduction as a core efficiency technology to reduce
new vehicle CO2 emissions and increase fuel economy. Lack of recognition about the potential for
vehicle mass reduction can run the risks of neglecting a major CO2- reducing technology, ignoring a
critical low- cost technology, and missing an opportunity to the set the stage for long- term electric- drive
technologies that may very well require mass- reduced vehicles.
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1. Introduction
Technology developments by the automobile industry, consumer preferences for vehicle
performance, and societal pressures on vehicle efficiency will ensure that there will be a constant
deployment of lower- mass vehicle concepts in new automobiles. This mass- reduction technology
deployment occurs with the piece- by- piece introduction of new reduced- mass parts, the use of advanced
materials in stronger designs, and the redesign of vehicle models that systematically optimize the use of
materials and design in a more comprehensive manner. These types of mass- reduction technology can
reduce the mass of vehicles, independent of the size, functionality, or vehicle class of automobiles.
A primary driver for reducing the mass vehicle designs will be the consistent regulatory push for
increased vehicle efficiency in major automobile markets. Standards that regulate the fuel efficiency or
carbon dioxide ( CO2) emissions of light duty vehicles have become the norm around the world. The
goals of the standards generally are to reduce petroleum use and the CO2 emissions associated with
automobiles. These standards take on many different forms, involve different ways of categorizing
vehicles, require different levels of stringency, and have different timelines for their implementation.
There are regulatory standards in Europe ( gCO2/ km), United States ( gCO2/ mile, mile/ gallon), China
( km/ L), Japan ( km/ L), Canada ( gCO2/ mile), South Korea ( km/ L, gCO2/ km), Taiwan ( km/ L), and
Australia ( L/ 100km) ( ICCT, 2009). Together, these programs encompass about 70% of 2009 world
automobile sales. These efficiency initiatives – or at at least those that do not index their standards to
mass – will drive the development of vehicle mass- reduction techniques along with a variety of engine,
transmission, and other vehicle efficiency technologies.
This study investigates trends and technical research related to the development of reduced- mass
vehicle designs and their potential importance for the efficiency of future vehicles. The report is
structured as follows. After this introduction section, Chapter 2 reviews a number of basic weight- related
trends in the U. S., including a summary discussion of a number of fundamental relationships in vehicle
attributes of weight, performance, and CO2 emissions. Chapter 3 analyzes trends related to materials and
vehicle structural changes that allow for the reduction of vehicle weight, highlighting a variety of mass-reduction
concepts that are now emerging in production vehicles. Also within Chapter 3, technical
literature on the potential for mass- optimized vehicle designs is examined and findings from a number of
major engineering design studies are reviewed. Chapter 4 provides a discussion of the implications of
these vehicle mass reduction trends for future policy. Chapter 5 briefly summarizes major findings.
2. Background
Some background is provided in this section to put the rest of this report on vehicle mass reduction
in context. This section outlines basic vehicle mass trends in the U. S., the relationship between mass and
other vehicle attributes, the distinction between mass- reduction technology and downsizing, and the basic
breakdown of vehicle mass by the various components of the vehicle.
Vehicle mass, or more typically measured as weight in the U. S., has changed substantially in
various automotive markets over different time periods. Light- duty vehicles sold in the U. S. over the past
35 years exhibit how weight trends can shift under different market and regulatory situations. Figure 1
shows the weight trend for light- duty vehicles, as well as for the two major categories within light duty
vehicles ( based on data from U. S. EPA, 2009a). The historical shifts in the U. S. auto market over this
period show both periods of decreasing and increasing weight. From 1975- 1980, the time period of the
onset of federal fuel economy standards, as well as higher fuel prices and drastic world oil price
fluctuations, there was a 21% decrease in average new light duty vehicle weight ( with a 25% decrease for
cars and 9% for light trucks). However, following that time period was a period of stable fuel economy
standards and relatively low or stable fuel prices, resulting in rather different vehicle attribute trends.
During the period from 1987- 2009, the shift has been toward heavier vehicles, with a 28% weight
increase for new light duty vehicles over that span ( 27% weight increase for cars, 17% for trucks).
During that span, the highest year- on- year increase in vehicle weight was 3%, and the annual average
increase was 1.1%.
2
Figure 1. Light duty vehicle weight trends for model years 1975 to 2009 ( U. S. EPA, 2009a)
The presentation of data in the above Figure 1 involves aggregated data on the weight trend in the
new vehicle fleet. Underlying the overall vehicle weight trend is a handful of factors related to consumer
shifts in vehicle category and size, as well as differences in the content of the vehicles. Just as the
average light duty vehicle weight increases due to consumer shifts from cars to trucks, so to do the car
and truck average weight increase due to the increased purchase of existing models that are in heavier
vehicle classes within those categories ( e. g., compact sedan to mid- size sedan shift). These fleet
composition sales shifts are separate trends from the concurrent general increases in vehicle weight that
come from vehicle model redesign changes that tend to see increases in vehicle content ( e. g., air
conditioning, safety equipment). Based on a General Motors study, the content increases due to such
equipment changes on a vehicle could amount to approximately 300- 400 lbs ( Glennan, 2007). This
would imply that equipment changes represent a smaller portion – about 20- 40% – of the overall light
duty vehicle weight trend shown in Figure 1 ( see also Corus, 2009).
The remainder of the overall mass increase would then come primarily from the shifts toward
vehicles of larger size and mass characteristics ( i. e., independent of vehicle content). Due to the relatively
recent development of U. S. size- indexed standards and the related tracking of size variables, there are not
comparable historical model year data for vehicle size to compare with the above vehicle mass weight
data. It is highly likely that data on vehicle size ( as measured by the footprint metric) has followed
approximately the same trend as vehicle mass on a percentage basis, due to the close statistical correlation
between vehicle size and mass variables. Vehicle size and mass relationships are investigated further
later in this report ( See, for example, Figure 10 for how current vehicle models’ size and mass are related).
To understand vehicle efficiency improvements that occur over time, multiple vehicle attributes
must be examined at once. The trade- offs that are involved with efficiency technologies and their
potential use toward vehicle performance ( e. g., maximum power, greater acceleration), vehicle size and
mass, and fuel economy have been analyzed extensively in the research literature. Vehicle designers and
powertrain engineers have continued to bring forth incremental efficiency improvements in vehicles’
aerodynamics, engines, and transmissions through redesign phases of vehicle models. However, how this
technology budget is utilized in the U. S. light duty vehicle fleet tends to differ over time, due to the level
of regulatory pressure to increase fuel economy, the changes in the price of petroleum, and consumer
reactions to market factors and automaker offerings.
Figure 2 shows vehicle attribute trends from the onset of U. S. Corporate Average Fuel Economy
( CAFE) standards in 1975 through model year 2009. In the figure, average new light duty vehicle weight,
acceleration performance, fuel economy, and weight- adjusted fuel economy are shown, with data from
U. S. EPA ( 2009a). The vehicle weight variable is the loaded test weight of vehicles. The acceleration
performance is U. S. EPA’s estimate of the time it takes to accelerate vehicles from rest to 60 miles per
hour ( mph) in seconds. The fuel economy variable is the combined ( city and highway), adjusted ( for on-road
conditions) measure of miles per gallon traveled. The “ efficiency” variable is the weight- adjusted
fuel economy of vehicles ( weight multiplied by fuel economy), and is a measure of the distance that a
3000
3400
3800
4200
4600
1975 1980 1985 1990 1995 2000 2005
Vehicle test weight ( lb)
Model year
Trucks
Cars and Trucks
Cars
3
vehicle can transport a ton, or 2000 lbs, of loaded vehicle weight on one gallon of fuel. This ton- mpg
measure is used here as a simple measure for overall vehicle efficiency, due to data difficulties in
attempting to more accurately portray the more true technical efficiency of engines, transmissions,
aerodynamics, vehicle weight, etc. All of the variables are sales- weighted average values for new
vehicles of the model year specified.
Vehicle weight
and acceleration
trends
Fuel economy and
weight- adjusted
efficiency trends
Figure 2. U. S. light duty vehicle trends for weight, acceleration, fuel economy, and weight- adjusted
fuel economy for model years 1975- 2009 ( U. S. EPA, 2009a data)
By showing the acceleration, weight, fuel economy, and the efficiency variables together, Figure 2
demonstrates the historical trade- offs that have occurred between these factors. Within that 1975- 2009
period, the only period for which major fuel economy increases were mandated was from 1975 to 1987.
During this early CAFE time period, when there was an increasingly stringent fuel economy standard,
vehicle weight was constrained – to either be held steady or be reduced on average – to aid in automaker
compliance with the fuel economy standards. Also during this time period, vehicle acceleration was
approximately stable. With these weight and acceleration variables constrained, new efficiency
technology was fully devoted to fuel economy improvement. As a result, average fuel economy
improved rather dramatically from about 13 mpg to about 22 mpg in those first twelve years of CAFE.
However since 1987, vehicles have, on average, become heavier and faster while fuel economy has not
shown marked or consistent increases. By showing the combined impact of vehicles getting heavier
while having approximately stable fuel economy from 1987 to 2009 in ton- mpg terms, the improvement
in vehicles’ technical efficiency is illustrated. This steady efficiency improvement from 1987 to today
went toward the production of heavier and faster vehicles – instead of toward increased fuel economy.
Such trade- offs with vehicle mass, performance, fuel economy, and efficiency are discussed and
analyzed in detail in a number of research studies ( Lutsey and Sperling, 2005; An and DeCicco, 2007;
Knittel, 2009; U. S. EPA, 2009a). Generally, these types of studies suggest how fuel economy could have
8
9
10
11
12
13
14
15
3200
3400
3600
3800
4000
4200
1975 1980 1985 1990 1995 2000 2005 2010 Acceleration 0- 60 mph ( sec)
Vehicle test weight ( lb)
Model year
Vehicle test weight
0- 60 mph acceleration time
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26
30
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42
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1975 1980 1985 1990 1995 2000 2005 2010
Vehicle ' efficiency' ( ton- mpg)
Adjusted fuel economy ( mpg)
Model year
Fuel economy ( mpg)
Mass- adjusted fuel economy ( ton- mpg)
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4
improved if other vehicle attributes were held constant. Some of these studies suggest that, due to the
technology advances of automakers’ engineering efforts, improvements in new vehicles’ technical
efficiency occur at a rate of about 1% to 2% per year, even in the absence of regulatory pressure to sell a
fleet of vehicles with higher fuel economy. However, as indicated from the Figure 2 trends, increases in
the overall average vehicle mass tend to consume any efficiency improvements that do indeed occur, and
therefore the fuel economy level does not reflect all of the naturally occurring efficiency improvements.
Included in these efficiency technologies that are “ unseen,” or not directly in evidence, are numerous
mass- reduction techniques that are incrementally introduced into vehicle models over time.
The average mass of the existing fleet of vehicles is directly linked to the energy consumption of
vehicles, due the physical requirement of the vehicles’ powertrain systems to accelerate and maintain
various speeds for the inertial mass of the vehicle. Due to the oxidation of carbon in the combustion of
hydrocarbon gasoline and diesel fuels, vehicle CO2 emissions are, in turn, closely linked to the mass of
vehicles. Based on the model year 2008 vehicle fleet, Figure 3 shows this relationship between vehicles’
weight and CO2 emission rate on the combined city- highway U. S. Federal Test Procedure ( FTP). In
addition to the new 2008 vehicle fleet on the plot are the fourteen sales- weighted corporate averages CO2
emission rates and vehicle weights for major automakers. Based on the linear relationship between
vehicle models’ curb weight and CO2 emission rates shown, a 10% change in vehicle weight within the
existing fleet of vehicles is associated with an approximate 8% change in vehicle CO2- per- mile emissions.
Figure 3. U. S. automobile weight and CO2 emissions
Although Figure 3 shows an important fundamental relationship between a fleet of vehicles’ weight
and CO2 emissions, an important distinction must be made between this current fleet relationship and the
potential for “ mass- reduction technology” that exists on all vehicles of all sizes. A shift in sales within an
existing fleet is generally referred to as downsizing and it involves a shift in fleet composition toward
vehicles that are both smaller and have reduced weight, but does not involve a redesign of existing vehicle
models. Mass- reduction technology, on the other hand, involves the use of higher strength materials and
mass- optimized vehicle structures to redesign vehicle models to have lower mass but without change in
vehicle size or functionality.
Based on a number of studies, the physical relationship between vehicle mass and its technical
efficiency ( measured approximately as either in CO2 emission rate or fuel consumption) is well
established. Often the relationship is expressed as an elasticity between mass and fuel economy to define
the effect in percent fuel economy increase that results from a percent vehicle mass reduction. The
research consistently shows elasticities whereby a 10% decrease in the mass of a conventional vehicle
results in a 6% to 8% decrease in the fuel consumption rate ( on standard regulatory test cycles) if the
vehicles’ performance is kept constant ( see, e. g., Casadei and Broda, 2008; Bandivadekar et al, 2008;
FKA, 2007; Pagerit, et al, 2006). The range in the estimated elasticity is primarily related to which
performance variables ( e. g., 0- 60 mph acceleration) are kept constant and which drive cycles are
examined. When other factors like towing requirements and hybrid drivetrains are considered, the
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5
relationship can change somewhat. Figure 4 shows this vehicle mass- to- CO2- emission relationship for
vehicle mass reductions up to 35%. As shown, a 30% mass reduction is equivalent to an 18% to 24% CO2
emission rate ( and fuel consumption) decrease.
Figure 4. Effect of mass- reduction technology on CO2 emission rate for constant performance
Because this report is focused exclusively on mass- reduction technology it is important to
emphasize the distinction between technologies for improved mass- optimization and downsizing. Figure
5 illustrates this distinction by showing hypothetical examples of fleet downsizing and mass- reduction
technology. In the left side of the figure, the example of Honda selling more Civics and less of the larger
Accord models shows fleet downsizing. On the other hand, the hypothetical example of mass- reduction
technology example of Honda, using higher strength materials and mass- optimized designs to reduce the
mass of each model by 10%, is shown on the right. Sometimes downsizing ( or increased size trends, too)
can confuse or confound the analysis of mass- reduction technology trends; however these are distinctly
different factors. Both of these approaches yield lower CO2 emissions and a lower average vehicle mass,
but the fleet downsizing approach requires a shift in consumer purchasing. The focus of this technology
review is exclusively on the mass- reduction technologies of vehicle models through advanced material
substitution and optimized redesign – not on fleet or per- vehicle downsizing.
Fleet downsizing:
Shift in fleet composition toward smaller vehicles
( without redesign of vehicle models for lower mass)
Mass- reduction technology:
Redesign of vehicles to have the same size but lower mass
( without vehicle sales shift or models getting smaller)
Figure 5. Distinction between fleet " downsizing" and vehicle " mass- reduction technology"
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5%
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20%
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GHG emissions ( gCO 2 e/ mi)
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Accord
Reduced sales
Increased sales
125
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GHG emissions ( gCO 2 e/ mi)
Vehicle footprint ( ft2)
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Accord
Both models redesigned with
mass- reduction technology
6
As further background for this report on concepts for reducing vehicle mass, a breakdown and
description of vehicles’ mass characteristics is provided here. The weight of a given vehicle can be
partitioned by its material composition or by its functional vehicle systems. Because much of mass-reduction
technology research revolves around particular systems, conventional system categories are
summarized and defined here. Table 1 shows an approximate breakdown of vehicle systems, with ranges
to show the approximate variation seen in various existing vehicle designs. One of the major systems of
the vehicle is the body, or sometimes referred to as the “ body- in- white.” The body represents about a
quarter of the overall vehicle mass and is the core structure and frame of the vehicle. The body is so
fundamental to the vehicle, that sometimes it is the only portion of the vehicle that is researched, designed,
and analyzed in mass- reduction technology studies, because the other systems are not as sensitive to the
structural integrity of the vehicle. The other two most prominent vehicle categories are the powertrain
and the suspension systems; each of these typically makes up about one- fifth to one- quarter of the vehicle
mass. After these systems, the interior, closures, and miscellaneous ( including electronic, lighting,
thermal, etc) make up the remaining vehicle systems.
Table 1. Vehicle mass breakdown by system and components
Approximate vehicle
mass breakdowna System Major components in system
Body- in- white Passenger compartment frame, cross and side beams, roof
structure, front- end structure, underbody floor structure, panels
Powertrain Engine, transmission, exhaust system, fuel tank
Chassis Chassis, suspension, tires, wheels, steering, brakes
Interior Seats, instrument panel, insulation, trim, airbags
Closures Front and rear doors, hood, lift gate
Miscellaneous Electrical, lighting, thermal, windows, glazing
a Based on Stodolsky et al, 1995a; Bjelkengren, 2008; Lotus Engineering, 2010; the actual system definitions and system
component inclusion can vary, and percentage weight breakdown can vary substantially by vehicle
There are not perfect definitions or conventions that are applied in the literature for the vehicle
system categories and the components included within each category. For example, sometimes the
general term “ body” can more broadly refer to all vehicle parts but the powertrain and the chassis, and
therefore this definition makes the body about half of the overall vehicle mass. Often times the term
“ glider” is used to include all of the vehicle parts except for the powertrain of the vehicle. This report
references and summarizes many different studies on vehicle mass characteristics. As a rule, this report
tries to adopt the Table 1 definitions and make note when other conventions are applied in the various
studies that are referenced.
3. Vehicle mass reduction: Survey of trends and technologies
There is a diverse array of mass- reduction techniques that have been and are being used in
automobiles to improve efficiency and performance. The mass- reduction techniques can be seen through
historical trends in vehicle designs, new vehicle designs that are currently emerging in vehicles, and
concepts for future vehicle model redesign. Mass- reduction can occur in smaller incremental ways, for
example reducing the mass of vehicle parts piece- by- piece, or through a more fundamental whole- vehicle
redesign. This chapter provides a survey of mass- reduction technology trends, vehicle mass
characteristics among the existing vehicle fleet, production vehicle models with advanced mass- reduction
techniques, and vehicle concepts for the future.
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3.1. General technology trends
Historical vehicle mass reduction trends include major transformations in the materials used in the
design and construction of vehicles. Figure 6 shows the progression of vehicle materials from a long-term
historical perspective ( from Taub et al, 2007). The first mass- produced vehicles were primarily
constructed from wood, but quickly the primary dominant vehicle material became steel due to its greater
durability and higher strength. As vehicle designs and the available materials evolved, a greater diversity
of materials has been utilized for the more specialized parts of increasingly complex vehicles. Over the
years the modern automobile has seen a fundamental shift its composition toward higher strength steels,
aluminum, plastics ( including various polymers and composites), and other materials.
Figure 6. Historical shift in vehicle composition by mass ( based on Taub et al, 2007)
Within the vehicle composition shift, the most dramatic increases by mass in recent years are for
high strength steels and aluminum. Generally many of the milder, low- carbon steel parts of vehicle
powertrains and body structures have increasingly and incrementally moved toward higher strength steels.
The higher strength steels in turn bring forth structural designs that are simultaneously stronger and lower
in mass ( because they use less overall steel material). High strength steel ( HSS) alloys continue to be
more widely used across almost every vehicle system, including various powertrain components, steering
wheels, front- end structures, chassis, beams, and closure body panels. The above figure and other data
show how on average, high- strength steel content has about doubled in the past two decades to make up
13% of 2007 vehicles ( Taub et al, 2007; Ward’s Automotive, 2009). Within this trend, there are
particular advanced high strength steel ( AHSS) alloys that have seen particularly fast growth ( Keith,
2010). Such prominent AHSS materials include dual phase, martinsitic, and boron steels. Individual
vehicle models and some companies have incorporated these advanced steels much more quickly than the
fleet average. For example, the body of the Honda Civic went from 32% to 50% HSS when redesigned
for 2006 ( Krupitzer, 2009), the Mercedes C- class jumped from 38% to 74% HSS in its body redesign
( Gildea, 2007), and the BMW X6 has 32% of its body and closure structures composed of AHSS
( Steelworks, 2009). Estimates from Ducker Worldwide indicate that the automobile industry will see an
annual increase in AHSS of about 10% through 2020 ( AISI, 2009). Looking at automaker- by- automaker
average material composition, there are considerable differences in the use of high- strength steels.
Compared to the average 2009 usage of about 14%, some automakers have greater than 20% AHSS while
others have less than 10% AHSS ( Schultz and Abraham, 2009).
Similarly, lower density aluminum alloys continue to replace the milder, lower carbon steels.
Much of the overall vehicle composition shift toward aluminum has come with increasing use of
aluminum in engine cylinder heads and blocks, transmission parts, and wheels. Aluminum has gone from
about 5% of light duty vehicles in the late 1980s to about 9%, or over 325 lbs per vehicle today
( Stodolsky et al, 1995; Brooke and Evans, 2009). Most cylinder heads are aluminum, and now engine
blocks made from aluminum in U. S. light duty vehicles passed 50%, surpassing steel in this area for the
first time ( Simpson, 2006). Along with engine cylinders heads and blocks, aluminum is competing to
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8
replace many traditional steel components in vehicles, including valve covers, torque converter and
transmission housings, crankcases, control arms, suspension links, cradles, steering wheels, door frames,
dashboards, sheet panels ( e. g., roof, door, hood), and beams ( Caceres, 2007). Along with these areas,
relatively new areas being explored for aluminum include all aluminum bodies, bumpers, crash-management
systems, and unibody construction ( Keith, 2010).
Other than increased use of high- strength steel and aluminum, there are also substantial increasing
trends for the use of magnesium. Magnesium is least dense of the primary automotive metals, at about
30% lower density than aluminum and 75% lower density than steel and is therefore seen as a promising
potential lower mass metal substitute ( Kulekci, 2008). However, currently magnesium only makes up
about 10 lbs, or 0.2%, of the average new U. S. vehicle ( Ward’s Automotive, 2009). New magnesium
parts have been commercialized in a number of vehicle models for several years now. For example,
Volkswagen applied 20 kg of magnesium in its cars in the 1970s and refers to the more recent expanded
magnesium application into instrument panels, driveline components, and the gearbox housings as a
magnesium renaissance ( Friedrich and Schumann, 2001). Although current magnesium use in vehicles is
low, some forecasts suggest that magnesium could become a major automotive component in the near
future. The same Volkswagen engineers suggest that 60 kg magnesium per vehicle is realistic and 100
kg per vehicle of magnesium is conceivable in the 2010- 2020 timeframe ( Friedrich and Schumann, 2001).
A study by the U. S. Council for Automotive Research indicates that vehicle magnesium content could
increase to 350 lbs by 2020 ( U. S. AMP, 2006). Ford forecasts the use of about 250 lb of magnesium
components per vehicle by around 2020 ( AEI, 2010b). Some early magnesium applications are seen in
roof frames, cross beams, interior components like the instrument panel, steering column, steering wheel,
and engine cradle ( e. g., see Gerard, 2008).
Outside of the above three metal groups, there is also potential for automobile mass reduction with
the expanded use of plastics and polymer composites. These plastic materials are considerably less dense
than all the automotive metals discussed above, and, up to now, these materials have tended to fill many
of the non- structural functions of vehicles for example in many interior components. To illustrate their
low density compared to the rest of the vehicles’ materials, modern vehicles are about 8% plastic by mass,
but 50% plastic by volume ( Bandivadekar et al, 2008). Automobiles utilize a wide range of plastic types,
including polypropylenes, polyesters, and vinyl esters. These materials are utilized in hatches, roofs,
interior panels, instrument panels, and hundreds of other parts. Although primarily replacing non-structural
vehicle components, plastics have continued to make in- roads in bumper systems and in
composite beam applications, and a number of studies have found potential to supplant structural beams
and frame components ( Stodolsky et al, 1995b; Lovins and Cramer, 2004). Also included in this general
category are the more costly composites, like glass fiber and carbon fiber reinforced polymers. These
materials, to date, are used primarily in limited applications in low- production- volume vehicles.
Particular substitution possibilities for all of these materials are described and elaborated upon
further below in Section 3.4. The general applications of these automotive materials follow directly from
their material properties. Figure 7 shows the material properties of the main material options for the
construction of the various vehicle components. All the numbers shown in the chart are approximate and
should only be viewed as illustrative, as there are many different grades and types of the general materials
that are listed ( data are based on Caceres, 2007: U. S. DOE, 2006; Powers, 2000; Lovins and Cramer,
2004; Stodolsky et al, 1995b). Yield strength and cost are shown in logarithmic scale in order to
accommodate their large variation across materials. As introduced above, steel has historically taken on
almost all of the primary structural functions of vehicles’ body and chassis components. Increasingly,
lower density and higher cost alternative materials ( aluminum, magnesium, plastics) and stronger steels
that require less of their use are supplanting the lower carbon steels. Many plastics, despite their relative
high cost per mass and low strength, are still critical components due to how light and shapeable they are,
which enables lower fabrication costs ( e. g., sheet molded composite [ SMC]). The highest strength glass
and carbon reinforced composites and titanium alloy materials have remained expensive and rare in
automotive applications. In a more comprehensive material comparison, other factors would further
differentiate these materials’ relative advantages and disadvantages in terms of their stiffness, elongation
properties, creep deformation, corrosiveness, ductibility, reparability, etc.
9
Figure 7. Automotive material properties and approximate costs ( based on data from Caceres,
2007: U. S. DOE, 2006; Powers, 2000; Lovins and Cramer, 2004; Stodolsky et al, 1995b)
Despite the increased material cost of moving toward stronger and more mass- optimized metals
( HSS, aluminum, magnesium) and non- metals ( e. g., plastics, carbon fiber), their potential for net
component cost improvements keeps each one of them advancing and penetrating further within various
automotive applications. To demonstrate how this net cost decrease occurs, Figure 8 shows how the use
of higher strength steel alloys can affect material cost, material use, and overall cost. The figure shows
how, despite shifting toward more expensive materials ( up to 10% higher cost per mass), the reductions in
the use of that material reduce more substantially to actually reduce the part cost by more than 10%. The
example is for four particular grades of high- strength steel as potential substitutes for the B- pillar between
vehicle front and rear doors, using data from ThyssenKrupp ( Adam, 2009). However, the principle is
widely applicable – as similar trade- offs in material choice, material thickness, and the overall amount of
required material exist in many vehicle components and with different materials. This demonstrates how
stronger and more expensive materials that are utilzed in mass- optimized ways can be utilized with net
manufacturing cost savings.
Figure 8. Example of higher- strength, higher- cost materials achieving a net decrease in component
cost ( based on steel alloy options for B- pillar from Adam, 2009)
Another critical transformation in automobiles over the past couple decades is in the way that
vehicles have been constructed. Originally, vehicles were most commonly manufactured with a body- on-frame
construction, whereby a vehicle body structure and frame are independently built and they are later
combined ( e. g., bolted together) during the vehicle production process. Instead, unitized body, or
“ unibody” construction, all of the vehicle’s body components ( including body, side beams, panels, floor
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10
pan, roof) and the traditional chassis frame structure are constructed together as one integrated load-bearing
structure. Figure 9 depicts body- on- frame and unibody designs for two sport utility vehicles.
The innovation required more design planning, as many different body types ( e. g., sedan, station wagon,
limousine) could easily be placed on one existing frame. However, ultimately this led to a reduction in
components and weight of the overall body structure and related cost reductions.
http:// blogs. cars. com/ photos/ uncategorized/ 2008/ 06/ 09/ explorer_ chassis_ final. gif
http:// static. howstuffworks. com/ gif/ cg- suv- safety- 3. jpg
Body- on- frame Unibody
Figure 9. Illustration of body- on- frame and unibody vehicle construction
The use of unibody construction began to be deployed widely for smaller cars in the 1960s and
slowly took over as the dominant vehicle construction for larger cars through the 1980s. Currently
unibody construction represents nearly all of passenger car production and most of the smaller sport
utility vehicles ( i. e., crossover or car- based sport utility vehicles) production in the U. S. Unibody
vehicles represented about 59% of U. S. light duty vehicles in 2000 and about three- quarters of the new
vehicle fleet in 2008, and they are forecasted to continue this trend to be 80% of the 2015 new vehicle
fleet ( Schultz and Abraham, 2009). The remaining one- quarter of light duty vehicles that are
predominantly body- on- frame construction is comprised of the larger sport utility vehicles, full- size vans,
and pickups, as body- on- frame structure provides a more rigid structure that is well suited for high towing
capacity.
Improved design techniques have enabled a systems level design of vehicles. This is contrary to
the more common piece- meal approach, whereby an automaker or supplier changes one frame piece or
substitutes a new material incrementally, piece- by- piece. Tools like computer- aided design ( CAD) and
finite element analysis were pioneered in the 1980s. Then computer- aided engineering ( CAE) techniques
developed extensively through the 1990s, allowing automotive engineers to increasingly design vehicles
virtually while accounting for the interaction of vehicle parts in a much more sophisticated manner.
Some automotive engineers suggest that these past CAE and CAD efforts are just the beginning of such
new designing techniques for vehicle mass reduction. Advanced simulation tools, such as biomimetic
topology, help strategically target advanced high- strength steel material gauges and materials to shed
unnecessary vehicle weight on the order of 120 lbs from body structures ( Brooke and Evans, 2009).
Mass- optimization from a whole- vehicle perspective opens up the possibility for much larger
vehicle mass- reduction opportunities. For example, secondary mass- reduction effects, sometimes called
mass decompounding, can be very important ( see, e. g., Malen and Reddy, 2007; Bjelkengren, 2006).
Secondary mass- reduction is possible as reducing the mass of one vehicle part can beget further
reductions elsewhere due to reduced requirements of the powertrain, suspension, and body structure to
support and propel the various vehicle systems. New more holistic approaches that include integrated
vehicle systems design, secondary mass effects, multi- material concepts, and new manufacturing
processes are expected to help optimize vehicles for much greater potential mass reduction ( see, e. g.,
Friedrich and Schumann, 2001; Glennan, 2007; Goede et al, 2009; Lotus Engineering, 2010). The results
of these new design techniques are examined below.
11
3.2. The existing fleet of vehicle models
The above section introduces details and trends related to the composition and design of vehicles.
A broader way of examining vehicle mass characteristics is to look at a snapshot of the current vehicle
fleet. The fundamental vehicle size- to- weight relationship for the U. S. light duty vehicle fleet is shown in
Figure 10. The figure shows that, for a given vehicle size, it would be possible to approximately estimate
the weight of that vehicle, based on the current spread of vehicle models across all of the different
categories ( e. g., compact cars, to small sport utility vehicles, to large pickup trucks). Here, vehicle size is
measured as the area between the wheels ( i. e., wheelbase multiplied by average track width). Based on
this figure, it is also possible to pick out which vehicles are relatively heavy for a vehicle of that size
( above the regression line), and which vehicles are relatively light ( below the line). This important
distinction shows that within this basic size- weight spread of the vehicle fleet there is a large apparent
discrepancy in the weight characteristics of vehicle models: comparatively light vehicle models can be as
low as 25% below the line and comparatively heavy vehicle designs can be as high as 40% above the line
that defines the average model vehicle size- to- weight relationship.
Figure 10. Model year 2008 U. S. light duty vehicle curb weight and size
Noting the historical trade- offs in vehicle attributes ( as shown above in Figure 2), another way to
see how vehicle efficiency technologies are allocated in vehicles is to examine a snapshot of the existing
vehicle fleet – but with a look in particular at how the different automaker groups’ sales fleets compare to
one another. Figure 11 shows the sales- averaged size and weight of each automaker group, with the
spread of individual model year 2008 vehicles in the background. Within a single model year snapshot,
the sales- weighted average size and weight positions for each manufacturer gives some indication of how
different automaker groups are utilizing mass- reduction technologies in their vehicle models.
As is shown in the figure, automakers have different average vehicle size and weight characteristics.
Based on a linear regression of these automaker group average weights and sizes, various automakers
have relatively heavy vehicles for their size, while others are comparatively light. The relatively heavy
automaker averages ( those above the regression line) are companies that tend to specialize in luxury and
higher performance vehicles. Another factor in relative weights is the fraction of vehicles that are body-on-
frame construction. The heavier manufacturers tend to manufacture vehicles that, on average, have
higher power, higher- displacement engines, which result in an increase in the weight of the powertrain,
which is one of the heaviest vehicle component systems. Also, to the extent to which the automakers
specialize in luxury vehicle segments, their vehicles generally have increased premium content ( e. g.,
electronics, leather and power seats, sun- roofs, etc), which can be another factor in their relatively high
weight. Also shown in the figure is how some manufacturers are selling vehicles that have comparatively
low mass for their size. When compared to the industry trendline, Hyundai- Kia ( 8% lighter than the
industry trendline) and Honda ( 6% lighter) show relatively low average weight for the size of their
vehicles. Differences in automaker designs and material choices – their deployment of mass- reduction
technologies – are critical determinants in automakers’ relative weight- to- size characteristics.
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12
Figure 11. Sales- weighted average vehicle weight and size for each automaker group
3.3. Emerging mass- reduction technology and automaker plans
Building on the two previous sections on general vehicle mass trends and current automaker vehicle
fleet mass characteristics, this section summarizes near- term future automaker plans regarding the
emerging mass- reduction technologies. Recent media announcements, technical specifications, and
product developments from automakers provide a clear indication of the types of mass- reduction
technologies that will be utilized across new vehicles in upcoming years. Various automotive industry
plans are summarized here in order to highlight the diversity of different technology approaches that
industry is exploring, as well as to highlight common technology threads that cross the different company
strategies. The future plans that are recounted here are essentially all foreshadowed by the emerging
trends that were introduced above regarding advanced materials and mass- optimized vehicle designs.
From a general planning perspective, nearly all automakers have made some statement regarding
vehicle mass reduction being a core part of the overall technology strategy that they will utilize to achieve
future fuel economy and CO2 emission standards. Ford has stated that it intends to reduce the weight of
its vehicles by 250- 750 lb per model from 2011 to 2020 ( Ford, 2009). For context, the midpoint of that
range of reductions would correspond to a 12% reduction from the current Ford new light duty vehicle
sales fleet. Similarly, Nissan has a target of a 15% mass reduction per vehicle by 2015 ( Keith, 2010).
This reduction would represent over a 500- lb reduction from their 2008 light duty vehicle average.
Mazda’s statement about achieving a 220- lb reduction per vehicle ( Lago, 2009; GCC, 2008) is equivalent
to about a 6% reduction for the company’s current fleet, and Mazda has indicated that it is targeting an
additional 220- lb reduction by 2016 ( U. S. EPA, 2009b). Toyota stated that it could end up reducing the
mass of the Corolla and mid- size models by 30% and 10%, respectively, in the 2015 timeframe ( U. S.
EPA, 2009b). The low end of those targets, 10%, is equivalent to 350 lb per Toyota vehicle in 2008.
Federal U. S. regulators, in their assessment of automaker strategies to comply with upcoming fuel
economy and CO2 standards, pointed to the above announcements and mass- reduction technology trends.
In their final analysis, they suggested that the overall average per- vehicle mass reductions could be about
4% for new vehicles of model year 2016. Their analysis indicated that the response would differ
depending on the class of vehicles. Cars averaged a 3.8% mass reduction and light trucks averaged a
4.5% reduction. The smallest cars saw the smaller effects – a 75- lb reduction ( 2.8%) – while the effect
increased to a 376- lb ( 7.0%) reduction for the larger trucks ( U. S. EPA and NHTSA, 2010).
Although other automakers have been less forthcoming in providing such quantitative weight
reduction targets as those cited above, essentially every automaker does nonetheless indicate that future
fuel economy standards provide a major inducement for the commercialization of mass- reduction
technologies. In addition to the quantitative announcements above, automaker announcements indicate
that essentially every automaker continues to deploy a variety of mass- reduction technologies. For
example, in releases regarding products from General Motors, Chrysler, Volkswagen, Porsche, Audi,
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13
Mercedes, and BMW, there are statements about wider commercialization of lighter front- wheel drive
architectures, lighter interior components, increased use of less- dense materials, multi- material use, and
mass- optimized vehicle design techniques ( see, e. g., GMC, 2009; Gerard, 2008; Chrysler, 2009; Goede et
al, 2009; Stahl, 2010; EAA, 2007; Tan, 2008; BMW, 2008).
Details on emerging technologies and product announcements from automakers provide some
definition on the types of mass reductions that can be realized from various technologies. It must be re-emphasized
here that the actual reduction in mass from any model year redesign has historically been
quite rare. Automobile engineers routinely refer to a model “ weight creep,” whereby vehicle models
incrementally increase in mass as they typically add size and more content. Analysis of particular models
( see, e. g., the progression of the Volkswagen Golf [ Lotus Engineering, 2010; EAA, 2007]) show the types
of year- to- year changes that are well known to automotive engineers due to vehicles getting larger, adding
content, and increasing in powertrain size and performance ( Also see Chapter 2, above).
Noting this historical incremental upward mass creep trend of vehicles, many “ mass reductions”
can occur alongside increases in content and overall vehicle mass. These unseen reductions in vehicle
component mass can be observed in isolation by examining changes in individual parts of new and
redesigned vehicles. Therefore quantifying the impact of emerging mass reduction techniques requires
the isolation of particular parts or systems ( e. g., the engine, the body, smaller parts). Although most such
mass reductions within current vehicles cannot always be definitively known or quantified, in some cases
automakers release small amounts of information related to innovations in mass- reduced parts when they
publicly release and promote new models.
Table 2 summarizes vehicle components that have seen mass- reduction innovations in material use
or design in automotive applications. As shown, there is a large array of different measures, big and
small, being utilized to reduce component mass within vehicles. The mass reductions are taken from
many different sources, many of them being automaker press release materials for the vehicle models that
are distributed for automobile shows and reviews. Note the mass- reduction technologies are shown in
units of lbs, the more common U. S. unit. As enumerated in the table, there are many potential mass-reduction
opportunities throughout the vehicles’ various components and systems that have been utilized
in production vehicles. However, there are countless other measures that are less publicized and more
subtle than those that are documented here. Some of the innovations ( e. g., high- strength steel in all body
parts; aluminum engine and wheels) are relatively widespread, whereas others are in lower volume
production, are just emerging, or are relatively rare.
Engine mass savings result from increasing the use of high- strength steels, aluminum, and
magnesium components across the engine and its auxiliary components. Some Ford models found
reductions of about 100 lbs when switching to aluminum or aluminum- magnesium alloy engine blocks
( see, e. g., Tyll, 2010; Kulekci, 2008). Various other engine- related components can be switched to less
dense components like valves, connection rods, crankshafts, manifolds, and the engine cradle for weight
reductions that vary from 1 to 12 lbs for technologies that have been used by General Motors, Honda,
Porsche, and Audi ( Kulekci, 2007; U. S. AMP, 2009; Gerard, 2008).
The switching of many body parts to aluminum has been embraced by a number of automakers,
especially Audi and Jaguar. Honda first produced the all- aluminum body Acura NS- X in 1990 ( Muraoka
and Miyaoka, 1993). Since, Audi has increasingly utilized aluminum in the frame of its vehicles. The
2000 Audi A2 in Europe was among the early production vehicles with a body entirely made of
aluminum, resulting in about a 40% reduction in the weight ( Autointell, 2000). The model’s primary
weight savings of 295 lb from the aluminum body begat another 165 lb in secondary reductions via the
drivetrain, motor, and chassis systems ( EAA, 2007). The larger Audi A8 sedan uses 1147 lb of aluminum
( EAA, 2007) in its aluminum- intensive design. This amount of aluminum amounts to about 25% of the
current model’s overall curb mass and is almost three times the average U. S. vehicle aluminum
composition. Audi has continued to expand these aluminum mass- reduction concepts into other vehicle
models. For example, the TT model for model year 2008 used aluminum extensively for a 220- lb weight
reduction, the model year 2011 A6 uses Audi’s second generation of space frame innovations for a 50%
reduction in body weight, and Audi could apply the technology to the A3 and Q7 ( Brooke and Evans,
2009). Also, the latest A5 prototype uses the aluminum frame for a 242- lb reduction ( Lavirnc, 2009).
14
Table 2. Component weight- reduction potential from technologies on production vehicles
Vehicle
system Subcomponent New material or technique a
Weight
reduction
( lb) b
Example automaker
( models) c Source( s)
Block Aluminum block 100 Ford ( Mustang); most vehicles Tyell, 2010; Ford, 2010
Engine, housing, etc Alum- Mg- composite 112 BMW ( R6) Kulekci, 2008
Engine Smaller optimized molds ( Al) 55 Toyota ( Camry) Simpson, 2007
Valvetrain Titanium intake valves 0.74 GM ( Z06) Gerard, 2008
Connecting rod ( 8) Titanium 3.5 GM ( Z06); Honda ( NSX) Gerard, 2008
Driveshaft Composite 7 Nissan; Mazda: Mitsubishi ACC, 2006
Cradle system Aluminum 22 GM ( Impala) Taub et al, 2007
Power-train
Engine cradle Magnesium 11- 12 GM ( Z06) Gerard, 2008; US AMP, 200x
Intake manifold Magnesium 10 GM ( V8); Chrysler Kulekci, 2008: US AMP
Camshaft case Magnesium 2 Porsche ( 911) Kukekci, 2008: US AMP
Auxiliaries Magnesium 11 Audi ( A8) Kulekci, 2008
Oil pan Modular composite 2 Mercedes ( C class) Stewart, 2009
Trans. housing Aluminum 8 BMW ( 730d); GM ( Z06) Gerard, 2008
Trans. housing Magnesium 9- 10 Volvo; Porsche ( 911); Mercedes;
VW ( Passat); Audi ( A4, A8) Kulekci, 2008; US AMP
Unibody design Vs. truck body- on- frame 150- 300 Honda ( Ridgeline); Ford; Kia;
most SUV models Honda, 2010; Motor Trend, 2009
Frame Aluminum- intensive body 200- 350 Audi ( TT, A2, A8); Jaguar ( XJ);
Lotus; Honda ( NSX, Insight)
Brooke and Evans, 2009;
Autointel, 1999: EAA, 2007;
Audi, 2010
Frame Aluminum spaceframe 122 GM ( Z06) Taub et al, 2007
Panel Thinner, aluminum alloy 14 Audi ( A8) Audi, 2010
Body Panel Composite 42 BMW Diem et al, 2002
and
closures Doors ( 4) Aluminum- intensive 5- 50 Nissan ( 370z); BMW ( 7); Jaguar
( XJ)
Keith, 2010; BMW, 2008; Birch,
2010
Doors ( 4) New production process 86 Porsche ( Cayenne) Stahl, 2010
Door inner ( 4) Magnesium 24- 47 Kulekci, 2008; US AMP
Hood Aluminum 15 Honda ( MDX); Nissan ( 370z) Monaghan, 2007; Keith, 2010
Roof Aluminum 15 BWW ( 7 series) BMW, 2008
Lift gate Magnesium 5- 10 Kulekci, 2008; US AMP
Chassis Aluminum 145 Porsche ( Cayenne) Carney, 2010
Chassis Hydroformed steel structure,
tubular design 100 Ford ( F150) FordF150. net, 2010
Steering wheel Magnesium 1.1
Ford ( Thunderbird, Taurus);
Chrysler ( Plymouth); Toyota
( LS430); BMW ( Mini); GM ( Z06)
Kulekci, 2008; Gerard, 2008
Suspen.
and Steering column Magnesium 1- 2 GM ( Z06) Kulekci, 2008; Gerard, 2008; US
AMP
chassis Wheels ( 4) Magnesium 26 Toyota ( Supra); Porsche ( 911);
Alfa Romeo Kulekci, 2008; US AMP
Wheels ( 4) Lighterweight alloy, design 13 Mercedes ( C- class) Tan, 2008
Brake system Heat dissipation, stainless steel
pins, aluminum caps 30 Audi ( A8) Audi, 2010
Tires Design ( low RR) 4 Mercedes ( C- class) Tan, 2008
Suspension Control arms ( 2) 6 Dodge ( Ram) SSAB, 2009
Seat frame ( 4) Magnesium 28 Toyota ( LS430); Mercedes
( Roadster) Kulekci, 2008; US AMP
Interior
Instrument panel Magnesium 7- 13
Chrysler ( Jeep); GM; Ford
( Explorer, F150); Audi ( A8);
Toyota ( Century); GM
Kulekci, 2008; US AMP; Taub
et al, 2007
Dashboard Fiber- reinforced thermoplastic 18 VW ( Golf) Stewart, 2009
Console and
shifter
Injection molded glass
reinforced polypropylene 5 Ford ( Flex) Stewart, 2009
Misc. Windows Design, material thickness 3 Mercedes ( C- class) Tan, 2008
Running board Glass- reinforced polypropylene 9 Ford ( Escape) Stewart, 2009
a These technologies can include a change in design, a reduction in parts, a reduction in material amount, and use of various metallic alloys;
note that weight ( lb) and mass ( kg) variables are used in this report. 1 kg = 2.205 lb.
b Weight reduction estimates are approximate, based on media sources and technical reports
c A number of these models are not available in the U. S.; some model names have changed in recent product changes
Along with the mass- reduction technology concepts being commercialized by Audi, other
automakers also claim “ first” status in developing aluminum vehicle bodies, although generally in lower
production volume performance and luxury vehicles with more limited production. Lotus has also
15
employed aluminum body technology in its mass- efficient sports cars through the 1990s. Honda and
Jaguar have both employed aluminum sheet body structures. Honda, with its Acura NS- X in 1990,
offered the first all- aluminum body, chassis, and suspension. The NS- X’s aluminum design reduced
body- in- white weight by 309 lb ( 40%) and overall vehicle weight by 441 lb ( Komatsu et al, 1991;
Muraoka and Miyaoka, 1993). Meanwhile, Honda, as mentioned above, currently is one of the bigger
users of high- strength steel in its vehicle bodies to result in one of the more mass- efficient fleets. The
Jaguar XJ design pioneered its own full aluminum body and also extensively utilizes high- strength steels
and composites, reduces adhesive use by 10%, reduces the required parts by 15%, and uses glass-reinforced
plastics for a 700- lb reduction in vehicle weight ( Birch, 2010).
Also highlighted in Table 2 for mass- efficient body innovations being deployed is the use of
unibody construction for trucks. As introduced above, over three quarters of light duty vehicles in the
U. S. are unibody construction, with the remaining body- on- frame vehicles being mostly mid- size and
larger pickup trucks and sport utility vehicles. The only unibody pickup truck that has been
commercialized is the Honda Ridgeline, which is roughly estimated to offer an equivalent weight
reduction of 300 lb versus similarly equipped and powered competitor pickup trucks. Several reports
suggest that unibody design could eventually penetrate all larger light trucks for which there are not high
towing requirements. For example, the Ford Explorer would convert from body- on- frame to unibody for
a 150- lb weight reduction in upcoming years ( Motor Trend, 2009). Another automaker, Kia is
transitioning its Sorrento sport utility vehicle to a front- wheel- drive unibody layout and is considering a
unibody pickup that could be comparable to the Ridgeline ( Johnson, 2008).
Outside of the core body frame structure, mass- reduction technology features in other areas can add
up to substantial mass reductions. Lighter roof panels, beams, side panels are being deployed by many
different automakers. Thinner gage high strength steels and aluminum are the main substitutes, but some
limited magnesium is also being utilized. Within the suspension and chassis system, major mass
reductions are being found from aluminum wheels and redesigned braking systems. Also, more simply
( and without material substitution), many suspension and chassis parts can see secondary mass reductions
from reduction in their size that result from mass reductions elsewhere on the vehicle. In the interior,
magnesium substitution shows considerable mass reductions in the instrument panel and seat frames.
As mentioned above, Ford has committed to a 250 to 750 lb reduction in vehicle models’ weight by
2020. In recent model year redesigns, Ford appears to be getting an early start on this commitment. The
2009 Ford F- 150 saw an overall 100- lb reduction from its predecessor ( Brooke and Evans, 2009). Shifts
from larger cast- iron engine at Ford to all- aluminum ones result in a 100- lb weight reduction and
improved power- to- weight ratio, improved fuel economy, acceleration, handling, and steering precision
( Tyll, 2010; Ford, 2010). Ford’s use of plastics in new running boards, center console/ shifter assembly
netted additional reductions ( Stewart, 2009), and a new tubular steel chassis for the F150 pickup was
found to reduce that model’s weight by 100 lb ( FordF150. net, 2010).
Mazda’s redesign of its compact Mazda2 in 2008 resulted in a 100- kg mass reduction from the
previous year ( Brooke and Evans, 2009). As noted above, Mazda has installed a near- term target of a 100
kg ( 220 lb) mass reduction per vehicle for all its vehicles during model redesigns from 2011 to 2015;
Mazda’s logic is that improving current technologies ( engine, transmission, stop- start, mass reduction),
they can achieve a 30% fuel consumption improvement without hybrid technology ( Lago, 2009, GCC,
2008). For the Mazda2 model, a 100- kg weight reduction is equivalent a 10% mass reduction.
Although Porsche has not made such an across- the- board commitment regarding mass- reduction
technology as Ford and Mazda, its latest Cayenne model is among the largest of all year- on- year mass
reductions. The announced 400- lb reduction for the V- 8 Cayenne from model year 2010 to 2011 comes
from a combination of many mass- reduction technologies. The lower mass model uses high- strength
steel throughout; increased aluminum content in the chassis, suspension, hood, fenders, doors, and hatch;
a new production process for the doors; and a lower mass all- wheel- drive system. Despite adding 154 lbs
in additional equipment, the mass- reduction technology measures resulted in a net 400- lb overall
reduction for the 2011 Cayenne ( Carney, 2010; Stahl, 2010).
In some rare cases, vehicle models have had overall reductions in mass as a result of mass-reduction
technologies that more than offset the additional mass that the model may have taken ( due to
16
increased engine size, increased content, etc) at the same time. Several examples of whole- vehicle mass
reductions are shown in Table 3. A number of the examples include models that were listed above for
having mass- optimized parts or components, but these models generally applied mass- reduction
technologies in a more concerted way to actually achieve an overall reduction from the previous models’
curb mass. As shown, several models showed over 400 lb of weight reductions with a given design.
Note that, of these vehicle models, the ones with the largest weight reductions or 400 lbs or greater have
been relatively limited production of niche market models ( e. g., Honda NS- X, Audi A2, Jaguar XJ).
However, some vehicle models that achieved reductions of 100- 400 lb per vehicle have larger sales ( e. g.,
Mazda2, Cayenne, TT, 370z, F150).
Table 3. Examples of overall vehicle weight reduction from production vehicles
Vehicle make and
model ( year) Features Weight reduction,
lbs ( percent) Source ( s)
Honda NSX
( 1990)
• Nearly all aluminum body, chassis, suspension
• Increased aluminum content from 7% to 31%
• Body- in- white weight reduction from 350 to 210 kg ( 40%)
• Overall vehicle weight reduction from 1565 to 1365 kg
441
( 13%)
Muraoka and
Miyaoka, 1993
Audi A2 ( 2000)
• Aluminum- intensive space frame
• Direct body weight savings of 134 kg ( vs steel)
• Secondary savings of 75 kg from drivetrain, motor, chassis
461
( 18%)
EAA, 2007;
Autointel, 1999
Jaguar XJ ( 2010)
• Aluminum body frame, shell
• 10% reduction in adhesive use
• Glass- filled polymide/ ultra- high strength steel B- pillar
• Hydroformed A- pillar/ cantrail extrusion assembly
• Composites, glass- reinforced plastic molding
• Overall 15% few parts for the whole vehicle
717
( 15%) Birch, 2010
Porsche Cayenne
( 2011)
• Increased use of high- strength steel throughout
• Aluminum and high- strength steel chassis parts
• Aluminum fenders, hood, doors, rear hatch
• New production process for doors
• If subtract 154 lb of added features, 10% reduction ( 554 lb)
400
( 8%)
Carney, 2010;
Stahl, 2010
Mazda Mazda2
( 2008)
• Wide application of high- strength steels
• Aluminum engine head, block, wheels
220
( 9%) Brown, 2007
Audi TT ( 2008) • Aluminum- steel hybrid frame ( 58% Al, 42% HSS) 220
( 7%)
Brooke and
Evans, 2009
Ford F150 ( 2009) • Hydroformed steel body structure
• Use of tubular ultra high strength steel
100
( 2%)
FordF150. net,
2008
Nissan 370Z
( 2011)
• Wide application of high strength steels
• Aluminum door panels, hatch, hood
95
( 3%) Keith, 2010
Although they do not achieve particularly high efficiency or low CO2 emissions, and they do not
even achieve overall mass reductions in many cases, low- volume sport cars can exhibit inordinate
amounts of mass- reduction technology features due to the resulting improvement in performance. Like
the pioneering mass- efficient Honda NS- X model, the mass- reduction features on the recent Chevrolet
Corvette Z06, for example, are very advanced and too numerous to list here. A partial list includes
aluminum spaceframe, a carbon fiber- skinned balsawood core floor pan, magnesium roof frame,
hydroformed aluminum roof bow, aluminum allow transmission housing, high- strength steel crankshaft,
titanium intake valves, titanium connecting rods, magnesium steering column, carbon fiber wheel houses
( Gerard, 2008). Some of these types of mass- reduction innovations also occur on various models by
Audi, BMW and other automakers that specialize in performance models ( as shown above in Table 2).
Literally, it is safe to assume that these mass- reduction technology innovations at the scale of that
niche market Corvette Z06 are equivalent to over a hundred kilogram of mass reduction. However, as
utilized in such a performance- oriented model, the mass reductions are not realized. A clear reason for
the unseen nature of these models’ mass- reduction is that their powertrains are sized 2- 3 times the typical
vehicle size and power output for that vehicle size. For example the Corvette engine is a 6.0- liter 505-
horsepower engine, whereas an average U. S. vehicle of that weight has a 3- liter 200- horsepower engine.
As a result, these high- powered sports cars’ suspension systems and other vehicle components are also
17
beefed up to support the powertrain. Nonetheless, these types of innovative mass- reduction techniques
typically see their introductions in niche sports cars and can work their way into premium sports cars and
luxury vehicles before penetrating high- volume production vehicle models.
Another indication of automakers’ intent to deploy mass- reduction vehicle designs and increased
use of advanced materials is in the direct statements by automobile engineers and designers. Table 4
provides direct quotes from industry representatives from various media sources and technical reports.
These statements confirm that stronger advanced materials and mass- optimized designs are critical
components of automakers’ future vehicle plans. The quotes are from representatives of General Motors,
Ford, Nissan, Volkswagen, Fiat, and BMW and show a general importance of mass- reduction
technologies now and for future vehicle designs. Of course, the exact plans of automakers for the
different automobile manufacturing companies role out of new materials and designs is proprietary and a
part of their strategic product planning for the future. These direct statements, as well as the above
information related to mass- reduction plans of individual automakers and the increasing rollout of
emerging mass- optimized components, all suggest that mass- reduction technology is a major vehicle
efficiency technology lever for near- and mid- term commercialization.
Table 4. Automaker industry statements regarding plans for vehicle mass- reduction technology
Affiliation Quote Source
General
Motors
“ We use a lot of aluminum today- about 300 pounds per vehicle- and are likely to use more lightweight
materials in the future.” Keith, 2010
Ford
“ The use of advanced materials such as magnesium, aluminum and ultra high- strength boron steel offers
automakers structural strength at a reduced weight to help improve fuel economy and meet safety and
durability requirements”
Keith, 2010
Nissan
“ We are working to reduce the thickness of steel sheet by enhancing the strength, expanding the use of
aluminum and other lightweight materials, and reducing vehicle weight by rationalizing vehicle body
structure”
Keith, 2010
BMW
“ Lightweight construction is a core aspect for sustainable mobility improving both fuel consumption and CO2
emissions, two key elements of our EfficientDynamics strategy…. we will be able to produce carbon fiber
enhanced components in large volumes at competitive costs for the first time. This is particularly relevant
for electric- powered vehicles.”
BMW and
SGL, 2010
Volkswagen
“ Material design and manufacturing technologies remain key technologies in vehicle development. Only
integrated approaches that work on these three key technologies will be successful in the future. In addition to
the development of metals and light metals, the research on fibre- reinforced plastics will play a major role.”
Goede et al,
2009
Fiat
“ A reduction of fuel consumption attains big importance because of the possible economical savings. In order
to achieve that, different ways are followed: alternative engine concepts ( for example electric engines instead
of combustion ones) or weight reduction of the vehicle structure. Using lightweight materials and different
joining techniques helps to reach this aim”
Nuñez, 2009
Volkswagen “ Lightweight design is a key measure for reducing vehicle fuel consumption, along with power train
efficiency, aerodynamics and electrical power management” Krinke, 2009
BMW
“ A dynamic vehicle with a low fuel consumption finally demands a stiff body with a low weight. To achieve
the initially mentioned targets, it is therefore necessary to design a body which offers good stiffness values and
a high level of passive safety at a low weight.
Prestorf,
2009
BMW “ Light weight design can be achieved by engineering light weight, manufacturing light weight and material
light weight design”
Prestorf,
2009
Volkswagen “ Automotive light weight solutions are necessary more than ever to reduce CO2 emissions.” Stehlin, 2008
Volkswagen “ All the car manufacturers are working on advanced multi- material concepts that better exploit materials
lightening potential combining steel, aluminum, magnesium, plastics and composites.” Stehlin, 2008
Volkswagen “ Multi- Material Concepts promise cost effective light weight solutions” Stehlin, 2008
General
Motors
“ Undoubtedly many of the component and system innovations in the Z06 will provide a foundation for
technologies that will be incorporated in the electronically propelled vehicles of the future.” Gerard, 2008
General
Motors
“ One trend is clear – vehicles will consist of a more balanced use of many materials in the future,
incorporating more lightweight materials such as nanocomposites and aluminum and magnesium sheet.”
Glennan,
2007
Renault
“ To meet commitments on CO2 emission levels, it is important that we stabilize vehicle weight as from now,
and then start bringing it down. This requirement goes a long way to explaining the many current exploratory
programmes ( with names like 90g CO2 and 3 l/ 100 km), which will drive work on all factors having a bearing
on fuel consumption, including vehicle weight.”
Maeder, 2001
Honda
“ The desire for weight reduction for automobiles is increasing more and more … an increase of aluminum
material will surely be required. The company will be delighted if any technology to apply aluminum to the
car body developed by Honda to reduce car weight is useful for other automobile companies.”
Muraoka and
Miyaoka,
1993
Ford “ Excess weight kills any self- propelled vehicle... Weight may be desirable in a steam roller but nowhere else” Ford, 1924
18
3.4. Advanced mass- optimized vehicle designs
The above section and tables show the types of mass- reduction opportunities that occur with piece-by-
piece or component- level changes from vehicles that have been produced commercially. Although
those demonstrate significant mass reduction in vehicles, there is the potential for more substantial mass
reduction when the systematic and comprehensive redesign of vehicles is done with the expressed goal of
a mass- efficient vehicle. Whereas the above section on emerging mass- reduction technology illustrates
what is being done in the automobile fleet to reduce the weight of components, this section chronicles
more advanced vehicle redesign concepts that illustrate where future vehicle designs could be headed.
This section provides a summary of findings from a number of major research projects that have
sought to determine the mass- reduction technology potential for future vehicles. Although some of the
technology efforts described here are somewhat older, each of the projects demonstrates advanced mass-reduction
technologies that are currently not embraced widely by automakers and therefore are still highly
relevant. The vehicle concepts summarized here each involved a substantial research undertaking in
terms of analytical, engineering, and demonstration effort, and they each help to provide a better
understanding of the potential for future mass- efficient vehicle design. Before comparing various
technology aspects of the conceptual mass- optimized designs, brief summary tables are provided for the
following vehicle concepts:
• 1990- 2005: Honda NS- X ( Table 5)
• 2000: Ford’s P2000 ( Table 6)
• 2000: DaimlerChrysler’s ESX ( Table 7)
• 2000: General Motors Precept ( Table 8)
• 2000- 2004: Rocky Mountain Institute Revolution Hypercar ( Table 9)
• 2000- present: Audi A2 and A8 aluminum space frame ( Table 10)
• 2004- present: Jaguar all- aluminum XJ body ( Table 11)
• 2001: Porsche Engineering ULSAB Advanced Vehicle Concept ( Table 12)
• 2001- 2003: Ford/ US Army IMPACT Ford F150 ( Table 13)
• 2003- 2007: Auto/ Steel Partnership Future Generation Vehicle ( Table 14)
• 2004: ThyssenKrupp New Steel Body ( Table 15)
• 2005- 2006: DaimlerChrysler Dodge Durango Next Generation Frame ( Table 16)
• 2007- 2008: U. S. Advanced Materials Partnership magnesium- intensive vehicle ( Table 17)
• 2007- 2008: IBIS and Aluminum Association aluminum- intensive vehicle ( Table 18)
• 2005- 2009: Volkswagen- led European Super Light Car ( Table 19)
• 2010: WorldAutoSteel Future Steel Vehicle ( Table 20)
• 2010: Lotus Engineering Low and High Development Vehicles ( Table 21)
Table 5. Summary of Honda NS- X
Mass- reduction
features, findings
• Nearly all aluminum body, chassis, suspension; stamped aluminum frame
• Increased aluminum content from 7% to 31%
Mass- reduction
impact
• Body- in- white reduction: 309 lb ( 40%)
• Overall vehicle reduction: 441 lb ( 13%)
Sources
• Komatsu, Y., K. Ban, T. Ito, Y. Muraoka, T. Yahaba, K. Yasunaga, and M. Shiokawa, 1991. Application of
Aluminum Automotive Body for Honda NSX. Society of Automotive Engineers. 910548.
• Muraoka, Y. and H. Miyaoka, 1993. Development of an all- aluminum automotive body. Journal of
Materials Processing Technology. 38: 655- 674.
Status • Produced from 1990 to 2005
Illustrations
Y. Muraoka and H. Miyaoka/ Aluminum automotive body 659
Composeds pace
Rigidity
~ Rigiditya nds trength
Rigiditya nds trength
Fig. 6. Design concept of an aluminum body.
Extruded aluminum Press molded aluminum
656 Y. Muraoka and H. Miyaoka/ Aluminum automotive body
Fig. 1. All- aluminum sports Honda NSX ( after Ref. [ 1]).
19
Table 6. Summary of Ford P2000
Mass- reduction
features, findings
• Aluminum- stamped body, substitution of less dense metals and composites
• Aluminum ( 733 lb, or 37%) magnesium ( 4.3 lb, 3%), titanium ( 11 lb, 0.5%), and carbon fiber ( 8 lb, 0.4%)
• Secondary effects: smaller powertrain and other components
Mass- reduction
impact
• Body- in- white reduction: 476 lb ( 54%)
• Overall vehicle reduction: 1238 lb ( 38%)
Sources
• Automotive Engineering International, 2010. Battle of the metals: the aluminum angle.
http:// www. sae. org/ automag/ metals/ 10. htm Accessed April 9, 2010.
• Carpenter, J. A., E. Daniels, P. Sklad, C. D. Warren, M. Smith, 2007. FreedomCAR Automotive
Lightweighting Materials. Orlando, Florida. February 28.
Status • Prototype built and tested in late 1990s, similar Ford Prodigy unveiled at auto shows in 1999- 2000
Illustration
http:// us1. webpublications. com. au/ static/ images/ articles/ i6/ 0647_ 8lo. jpg http:// www. electrifyingtimes. com/ fordprodigy. jpg
Table 7. Summary of DaimlerChrysler ESX
Mass- reduction
features, findings
• Extensive use of plastics throughout the vehicle, including in body
• Structural injection- molded body panels and aluminum with aluminum frame
• Similar to Dodge Intrepid vehicle, but ESX3 body design resulted in 90% reduction in part count from steel
• Diesel- fueled mild hybrid ( 15- kW motor) with 72 mpg; projected cost premium of $ 7,500
Mass- reduction
impact
• Body- in- white reduction: 46%
• Overall vehicle reduction: 1238 lb ( 38%)
Sources
• Winter, D., 1998. “ Chrysler’s plastic car push.”
http:// wardsautoworld. com/ ar/ auto_ chryslers_ plastic_ car_ 2/. September 1.
• Jost, K., 2000. “ Dodge’s mild hybrid.” https:// www. sae. org/ automag/ globalview_ 05- 00/ 02. htm. May.
• Visnic, B., 2000. “ Injection molding for low- cost high mileage.” http:// wardsautoworld. com/ ar/ auto_
injection_ molding_ lowcost/. March 1.
Status • Prototype built and tested in late 1990s
Illustration
http:// www. autointell. net/ nao_ companies/ daimlerchrysler/ dodge/ dodge- esx3- 01. htm
Table 8. Summary of General Motors Precept
Mass- reduction
features, findings
• Aluminum intensive body, chassis, exterior panels, seat frames; carbon fiber bumper beams
• Novel chassis design with matrix composite brackets
Mass- reduction
impact
• Body reduction: 397 lb ( 45%)
• Overall vehicle reduction: 656 lb ( 20%)
Sources
• Automotive Engineering International, 2010a. Battle of the metals: the aluminum angle.
http:// www. sae. org/ automag/ metals/ 10. htm Accessed April 10, 2010.
• Autospeed, 2000. The 2000 PNGV Concept Cars. Autospeed Issue 97. http:// autospeed. com/ cms/ title_ The-
2000- PNGV- Concept- Cars/ A_ 0647/ article. html. September 12. Accessed April 10, 2010.
Status • Prototype developed in late 1990s; built in 2000
Illustration
http:// us1. webpublications. com. au/ static/ images/ articles/ i6/ 0647_ 11lo. jpg
20
Table 9. Summary of Rocky Mountain Institute Revolution
Mass- reduction
features, findings
• Vehicle optimization including integration, parts consolidation, advanced material substitution
• Carbon fiber- intensive body frame, plastic body panels, carbon- fiber drive shafts
• In- wheel motors, shared motor/ brake housing; advanced composite and aluminum front- end structure
• At $ 30,000 to $ 35,000 per vehicle, roughly cost- competitive with luxury sport- utility vehicles
Mass- reduction
impact
• Body- in- white reduction: 537 lb ( 57%)
• Overall vehicle reduction: 2080 lb ( 52%)
Source • Lovins, A. B., and D. R. Cramer, 2004. Hypercars ® , hydrogen, and the automotive transition. Int. J. Vehicle
Design 35: 50- 85.
Status • Prototype developed 2000- 2004
Illustration
Table 10. Summary of aluminum- intensive Audi space frame technology
Mass- reduction
features, findings
• Aluminum- intensive spaceframe body ( and powertrain, chassis, and suspension)
• Overall aluminum composition of 700 lb ( 34% of overall weight) for Audi A2
• Overall aluminum composition of 1150 lb ( 25% of overall weight) for Audi A8
• A2: body savings versus steel of 134 kg, secondary savings of 75 kg from drivetrain, motor, chassis
Mass- reduction
impact
• Body- in- white reduction: 300- 500 lb ( 30- 40%)
• Overall A2 vehicle reduction: 461 lb ( 18%)
Sources
• Autointell, 1999. World’s first volume- production aluminum car Audi A2 – fascinating technology and a
new form of agility. http:// www. autointell. com/ european_ companies/ volkswagen/ audi- ag/ audi- cars/ audi-a2/
audiag1112. htm.
• European Aluminum Association ( EAA), 2007. Aluminum in Cars. September.
• European Aluminum Association ( EAA), 2010. Automotive Aluminum Manual ( AAM).
http:// www. eaa. net/ en/ applications/ automotive/ aluminium- automotive- manual/
Status • Introduced in 1999 in compact A2, currently used in Audi A8
• New version of spaceframe being used in TT coupe, under consideration for A5, A6 and other models
Illustration
( A2, 1999)
http:// www. xwomm. com/ datagrip/ datagrip/ pictures/ gross/ acab_ 1h _ 2. jpg http:// www. xwomm. com/ datagrip/ datagrip/ pictures/ gross/ acab_ 1e_ 4. jpg
Illustration
( A8, 2002)
http:// www. xwomm. com/ datagrip/ datagrip/ pictures/ gross/ acab_ 3d_ 2. jpg http:// www. xwomm. com/ datagrip/ datagrip/ pictures/ gross/ acab_ 3b_ 2. jpg
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! R % - % = G = . , . * # ( ) ( , @ . + ! 1 / @ ! % E ; 5 , K " C + 0 . 1 " 1 ( , / - # & % ' H
! P & & J ' " # # & = 0 ( : # ' ( ! " = ( * ( ! . & ! 0 . + ! ( % ) . ) = : # " ( + & # 1 ! . - ( & ( ! G + ! S 0 % / ) = + & # . 0 . ) + # . = T / 1 ! . - & # $ 0 % , E 9 ! % 7 ; + , ! " 0 % / * " . 1 ! " . ! . = . @ ! 1 ! % & % . = 6 1 @ # # = 6 & % + . ! ( % ) % $ ! " # : # " ( + & # U 1 + # ) ! 0 # % ! V % = G 1 ! ( $ $ ) # 1 1 . ) = ! % 0 1 ( % ) . & 0 ( * ( = ( ! G 3 ; D % 0 , % 0 # " ( * " # 0 ! " 1 # = . ) 1
! W # 1 ( * ) # = $ % 0 . 9 ; ; ; ; ; ! J 5 , 1 # 0 : ( + # & ( $ # X + % , @ % 1 ( ! # - % = G ) % 0 $ . ! ( * / #
! Y % = / & . 0 # & # + ! 0 % ) ( + 1 . ) = 1 % $ ! ' . 0 # . 0 + " ( ! # + ! / 0 # . ) = + / 1 ! % , ! [ % ! # ) ! ( . & $ % 0 ! " # 1 ! ( + 5 # 0 @ 0 ( + # ! % - # + % , @ # ! ( ! ( : # ' ( ! " ! " # A # B / ( 0 $ 6 . ) = V Y \ & 1 ( 2 $ 6 ' ( ! " 1 ( * ) ( $ ( + . ) ! & G & % ' # 0 & ( $ # + G + & # F ( * / 0 # 9 ( & & / 1 ! 0 . ! # 1 ! " # , . ( ) ! # + " ) ( + . & $ # . ! / 0 # 1 % $ ! " # % . ! " % 1 # ! " . ! 0 # = / + # , . 1 1 . ) = ( , @ 0 % : # # $ $ ( + ( # ) + G 8
( 2 0 8 6 9 : 5 ; . 6 9 : 5 < . = 6 9 7
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
> ? + . # @ A # = " B : ? < # - 9 . 7 B A 7 < 5 : . A 4 5 - C - 5 6 3 . 5 # A 7 = 6 5 6 - 7 21
Table 11. Summary of aluminum- intensive Jaguar XJ
Mass- reduction
features, findings
• Aluminum- intensive body frame and shell; hydroformed A- pillar/ cantrail extrusion assembly
• Glass- filled polymide/ ultra- high strength steel B- pillar; composites, glass- reinforced plastic molding
• Overall 15% few parts for the whole vehicle, 10% reduction in adhesive use
Mass- reduction
impact
• Body- in- white reduction: 250- 350 lb ( 25- 30%)
• Overall vehicle reduction: 717 lb ( 15%)
Sources • Birch, S., 2010. “ Jaguar remakes XJ.” http:// www. sae. org/ mags/ sve/ 7547. March 4. Accessed April 8.
• European Aluminum Association ( EAA), 2007. Aluminum in Cars. September.
Status • Introduced in XJ in 2002; currently available
Illustration
Table 12. Summary of Porsche Engineering Advanced Concept Vehicle
Mass- reduction
features, findings
• Mass- optimized steel- intensive design; meet 2004 safety regulations; cost minimization is final priority
• Developed two vehicle designs on European C- class ( small hatchback) and PNGV- class ( mid- size sedan)
• Holistic approach to simultaneously consider all systems of the vehicle together
• Demonstrated for frontal, side, and rear impacts that are comparable with Four- and Five- Star vehicles
• Manufacturing assessment for new materials and fabrication methods demonstrates affordable design
Mass- reduction
impact
• Body- in- white reduction: 91- 99 lb ( 17%)
• Overall vehicle reduction: 472- 1042 lb ( 19- 32%)
Status
• Supported by American Iron & Steel Institute
• Called UltraLight Steel Auto Body – Advanced Vehicle Concepts ( ULSAB- AVC) program
• Engineering design study in 2001
Source
• Porsche Engineering Services Inc., 2001. ULSAB- AVC: Engineering Report: The design, materials,
manufacturing, performance and economic analysis of ULSAB- AVC ( Advanced Vehicle Concepts).
October.
Illustrations
C- class
hatchback
and Sedan
3.2. PRIMARY WEIGHT SAVINGS
Aluminium allows a saving of up to 50% over competing materials in many applications.
Typical relativec and average absolute weight savings of today’s main aluminium applications in mass- produced
cars are given below.
Typical relative and average absolute weight savings
Relative weight saving Absolute w. s. Market penetration
• Engine and transmission parts:
• Chassis and suspension parts:
• Hang- on partsd:
• Wheel rimse:
• Bumper systems:
For niche models, full aluminium bodies allow saving 30- 40% weight, and between 70 and 140kg, depending
on the size of the car.
c Relative to the weight of substituted parts
d Doors, bonnet, wings, boot
e Wheel rims are presently not always weight- optimised. However, 50% weight saving is achievable.
Figure 3
! - 10kg
0% 60%
Engineering Services, Inc..
􀀖
Body- In- White Concepts
􀀵 􀀬 􀀳 􀀡 􀀢 􀀍 􀀡 􀀶 􀀣 􀀀 􀁮 􀀀 􀀰 􀀥 􀀳 􀀀 􀀥 􀁎 􀁇 􀁉 􀁎 􀁅 􀁅 􀁒 􀁉 􀁎 􀁇 􀀀 􀀲 􀁅 􀁐 􀁏 􀁒 􀁔 􀀀
􀀪 􀁕 􀁎 􀁅 􀀀 􀀒 􀀐 􀀐 􀀑 􀀀
􀀣 􀁈 􀁁 􀁐 􀁔 􀁅 􀁒 􀀀 􀀖
􀀰 􀁁 􀁇 􀁅 􀀀 􀀓 􀀑 􀀀 􀀀
Figure 6.6.1- 1 C- Class tubular hydroformed body side members 3/ 4 rear
view
Figure 6.6.1- 2 C- Class tubular hydroformed body side members 3/ 4 front
view
Engineering Services, Inc..
􀀖
Body- In- White Concepts
􀀵 􀀬 􀀳 􀀡 􀀢 􀀍 􀀡 􀀶 􀀣 􀀀 􀁮 􀀀 􀀰 􀀥 􀀳 􀀀 􀀥 􀁎 􀁇 􀁉 􀁎 􀁅 􀁅 􀁒 􀁉 􀁎 􀁇 􀀀 􀀲 􀁅 􀁐 􀁏 􀁒 􀁔 􀀀
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Figure 6.8- 3 PNGV- Class closure structures including glass 3/ 4 front view
Figure 6.8- 4 PNGV- Class closure structures including glass 3/ 4 rear view
22
Table 13. Summary of Ford and U. S. Army IMPACT Ford F150
Mass- reduction
features, findings
• Intensive use ( and stated preference for) high- strength steels throughout the vehicle
• Heavy use of dual- phase steel structures, bake hardened steels, and reduced steel gage
• Body structure is almost 100% high strength steel
• Found substantial reductions of 18% or greater in all major truck systems ( powertrain, cab/ front, chassis,
pick- up box, closures, and interior)
• Final design had roughly the same percent steel composition ( most steel shifted to high strength alloys)
• Body designed for five- star government crash test rating for passenger side impacts ( computer analysis)
• Found most weight reduction came with cost savings
• The first 19% overall vehicle weight reduction ( 1000 lb) came at net zero cost
• The full 25% reduction came at a $ 500 increase in the total variable vehicle cost
Mass- reduction
impact
• Overall vehicle reduction: 1310 lb ( 25%)
• Body- in- white ( cab+ front- end) reduction: 130 lb ( 20%)
Status
• Joint project between Ford, American Iron & Steel Institute, University of Louisville, U. S. Army TACOM
• Developed and built redesigned Ford F150 over 1998- 2003
• Individual weight reduction techniques ( 60% of them) have been utilized in Ford model platforms in the six
years from IMPACT project completion in 2001 to the 2007 report.
Source • Geck, P. J. Goff, R. Sohmshetty, K. Laurin, G. Prater, V. Furman, 2007. IMPACT Phase II – Study to
Remove 25% of the Weight from a Pick- up Truck. Society of Automotive Engineers. 2007- 01- 1727.
Illustrations
Table 14. Summary of Auto/ Steel Partnership Future Generation Vehicle
Mass- reduction
features, findings
• Intensive use of high- strength steels to replace iron and milder steels throughout vehicle
• Use of higher strength steel enables thinner gages and redesigned components
• Passenger compartment: 30% mass reduction, improved crash performance, no additional cost
• Front- end structure: 32% mass reduction, no additional cost
• Rear chassis: 24% mass reduction, no additional cost
• Closures: 22% mass reduction, no additional cost
Mass- reduction
impacts
• Overall vehicle reduction: 20- 30%
• Body- in- white reduction: 204- 214 lb ( 30%)
Status
• Supported by the Auto/ Steel Partnership, conducted by Altair Engineering
• Series of design, engineering, cost, and crashworthiness analyses completed between 2003 and 2007
• Many demonstrated uses of high- strength steel and design techniques are being introduced and
commercialized gradually across new vehicle models today
Sources
• Altair Engineering, 2003. Lightweight SUV Frame: Design Development. May.
• Auto Steel Partnership ( ASP), 2005. Lightweight Front End Structure Project: Phase I & II Final Report.
• Auto Steel Partnership ( ASP), 2007. Future Generation Passenger Compartment. Phase I Report. June.
Accessed December 10, 2009.
• Heimbuch, R. A., 2009. “ Auto/ Steel Partnership: Hydroforming Materials and Lubricant, Lightweight Rear
Chassis Structures, Future Generation Passenger Compartment”
• Krupitzer, R., 2009. “ Automotive Steels and Future Vehicles.” Bloomberg Cars & Fuels Summit. Dec 1.
Illustrations
dots, in Figure 3 corresponds
the cost increase/ decrease for
one of the subsystems.
for each subsystem until the
combination of alternatives is plotted,
25%. This goal translates to
because the base vehicle was
Therefore, various combinations of
until 1300 lb weight reduction
cost penalty.
the Program Attribute Teams
Teams ( the PATs). For
Durability/ Corrosion Team,
vehicle attribute teams and the
Team were activity teams.
support the module teams,
segregate the people with
from an organizational
there was synergy in having
a single team.
teams that were involved in
supported the overall goal of
the Architecture Team, the
the Corrosion Team. The
not intended to necessarily
project, but was meant to set in
would point to future projects,
objectives to the project being
some of the most significant
survived to provide the design
! " # $ % & ' ' (
) * ( +
, - . / 0 1 2 3 4 . / 0
3 4 . 5 0 1 2 4 % 6 7 . 5 0
3 4 . 8 0 1 2 4 % 6 7 9 0 0 1 2 , : 5 0 0
3 4 9 0 0 1 2 4 % 6 7 9 5 0 1 2 , : ; 0 0
< = % = 2 > 2 ? 0 0 2 ) : @
! " # $ % & ' ( ) * + ( , * - . / 0 * 1 2 3 * 4 5 0 6 7 * 8 9 3 3 * : 9 ; < ( = 3
Figure 4
Adhesive bonding was used to bolster welds throughout
the cab, which helped to make the body structure more
solid. Through the application of adhesive bonding to
critical joints of the structure, panel gages could be
significantly reduced.
Given the fact that there were several architecture
constraints, based on the original design, the 57 pound
savings achieved was considered as very significant.
While the weight savings did not achieve the 25% target,
the 17% weight savings for the cab without the front end
was considered a success, especially in lieu of the fact
that some other systems of the vehicle were able to
easily overachieve the 25% bogie.
Highlights of the cab structure design were as follows:
• ! 57 pound ( 17%) weight savings through
redesign and/ or using high strength steels at
thinner gages.
• ! Several Cab Components were redesigned;
roof, rear reinforcement panel, door opening
panels, rockers, floor pans and underbody
vehicle. In September 2001, Ford delivered the Phase II
prototype to the U. S. Army Tank Automotive
Armament’s Command’s ( TACOM) National Automotive
Center.
! " # $ % & ' # ( ) * + ' ! ! ' , - . / 0 ' % 1 2 3 / + 4 + 0
! " # $ % & ' $ ( ( & ) $ * + , - ( & . / 0 / 1 & % 2 ( 3 & 4 5 6 7 8
Figure 12
As an interesting outcome of IMPACT Phase II, weight
savings was effectively accomplished throughout the
vehicle. The following table summarizes the weight
savings accomplishment for each " major" module of the
vehicle. Other minor subsystems ( e. g., electrical) also
contributed weight savings.
Module Weight Savings
( lbs.)
Weight Savings
(%)
Powertrain 249 18
Chassis 383 24
Cab/ Front End 130 20
Pick- up Box 61 25
Closures 181 29
Interior 121 28
The steel selection process was fairly conservative in
that we were targeting steel grades, one grade stronger
than the steel, which was being replaced ( Figure 13).
Probably the most interesting result of this study was that
the percentage of steel in the final vehicle remained the
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Figure 13
ACKNOWLEDGMENTS
The authors would like to gratefully acknowledge Motor Company, the American Iron and the U. S. Army ( National Automotive Center), University of Louisville as the primary financiers of this study. Mention should the contributions of Mississippi State Oakridge National Labs, and the numerous tier 1 and 2 participants, many of which materials and services free of charge for REFERENCES
1. ! ULSAB Consortium, UltraLight Steel American Iron & Steel Institute, Electronic 1.0, 1998.
2. ! ULSAC Consortium, UltraLight Steel Presentation, American Iron & Electronic Report 2.0, 1998.
3. ! Patton, R., Brehob, E., State, M., Furman, P., and Cummins, M., " Advanced Technologies for 21 st Century Trucks," Automotive Engineers, document number 3424, 2000.
Future Generation Passenger Compartment ( FGPC)
!
B- pillar 1
B- pillar 2
B- pillar 3
Roof Rail 1
Roof Rail 2
Roof Rail 3
Lower body
cross- bar
Kickdown
cross- member
IP Beam
Front Header
Rocker
Inner
!
!
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!
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$ ' 3 ' & - / ' 5 ! 5 % & # 3 $ ! - 3 ! + 0 / # 6 # 7 - / # + 3 ! 2 + % . 5 ! * - : ' ! + 3 . ; ! + 3 ' ! + 4 ! / * ' ! 0 + ) ) # 1 . ' ! ( < ! . + 2 - / # + 3 ) 8 ! = # 6 # . - & . ; > ! " # $ % & ' ! ( ? !
) * + , ) ! - . . ! @ ! 0 + ) ) # 1 . ' ! . + 2 - / # + 3 ) ! 4 + & ! / * ' ! 4 & + 3 / ! ) ' - / ! 2 & + ) ) A 6 ' 6 1 ' & 8 ! B $ - # 3 > ! + 3 . ; ! + 3 ' ! + 4 ! / * ' ) ' ! @ ! 2 & + ) ) A 6 ' 6 1 ' & ) !
2 - 3 ! 1 ' ! - 2 / # : ' ! # 3 ! - ! $ # : ' 3 ! 5 ' ) # $ 3 8 ! !
!
Pos 1
Future Generation Passenger Compartment ( FGPC)
!
!
!
! " # $ % & ' ( ) * ' + , - . / - 0 ' 1 2 . , ' 3 " 4 5 ' 6 / , 7 8 '
!
Future Generation Passenger Compartment ( FGPC)
!
! " # $ $ % & # & $ ' ( # $ ) * + , - #
! " . " # / ( 0 1 2 + - $ 3 4 & #
" # $ % & ' # ( ! ) * # + & , & + % $ & - . ) ! % / # ! ( # ) + / & 0 # ( ! & . ! 1 * * # . ( & 2 ! 3 4 ! !
! " 5 " # 2 3 + ' & # + 4 ' # 6 3 1 4 ' + / 7 # , 3 4 ' $ - $ 3 4 & #
$ $ % & # ) 8 9 : ; < # ' = > 8 ? @ A B C = # 6 A ? ? : = ? # D ) ' 6 E #
5 6 # ! 7 - 8 & . 9 ! " # , - / : % 0 ' # ! ; % / / & # / ! < 7 " ; = ! > % ) ! ( # 8 # ' - * # ( ! % . ( ! 8 % ' & ( % $ # ( 4 ! ? $ ! + - . ) & ) $ ) ! - , ! @ A ! * % / $ ) ! % . ( ! 6 % ) ! % !
: % ) ) ! - , ! B C D D E 9 F ! % ) ! ) * # + & , & # ( ! & . ! $ 6 # ! ? ? G H ! / # 9 I ' % $ & - . ) 4 !
!
5 6 # ! 0 % / / & # / ! > % ) ! * - ) & $ & - . # ( ! % + + - / ( & . 9 ! $ - ! $ 6 # ! / # 9 I ' % $ & - . ) 4 ! 5 6 # ! ' - + % $ & - . ! - , ! $ 6 # ! 9 / - I . ( ! * ' % . # ! > % ) ! + % ' + I ' % $ # ( !
, / - : ! J 7 K H H ! L B A ! : - ( # ' ! - , ! J M N O P + ' % ) ) ! 8 # 6 & + ' # ! - , ! Q R H 1 N P 1 K O F ! % . ( ! $ 6 # ! 0 % / / & # / ! > % ) ! * - ) & $ & - . # ( ! ) - ! $ 6 % $ !
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+ ' - ) # ) $ ! # ( 9 # ! - , ! $ 6 # ! ( # , - / : % 0 ' # ! 0 % / / & # / ! < ? V " = ! & ) ! W B D : : 4 ! !
!
5 6 # ! 0 % / / & # / ! > % ) ! 9 & 8 # . ! % . ! & . & $ & % ' ! 8 # ' - + & $ X ! - , ! C D E * 6 ! * # / * # . ( & + I ' % / ! $ - ! $ 6 # ! 8 # 6 & + ' # F ! % ) ! ) * # + & , & # ( ! & . ! $ 6 # !
/ # 9 I ' % $ & - . ) 4 !
!
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; % ) # ' & . # ! % . ( ! 7 - ( & , & # ( ! : - ( # ' ) ! > # / # ! I ) # ( ! & . ! $ 6 & ) ! % . % ' X ) & ) 4 !
!
!
!
! " # $ % & ' ( ) * ' + , - . / 0 1 ' 2 1 3 , 4 5 . / 0 1 ' 6 . 4 4 7 1 4 '
23
Table 15. Summary of ThyssenKrupp New Steel Body
Mass- reduction
features, findings
• Developed mass- reduced vehicle using higher strength steels, tubular steel construction, new forming
techniques ( e. g., hydroforming), based on compact van Opel Zafira, which is popular in Europe
• Examined stiffness, crash, and impact load path
• Cost impacts: benefits from reduced materials ( 8%), assembly ( 2%), and tooling ( 4%), but increased
component manufacturing costs ( 16%)
• Estimated approximate net 2% increase in manufacturing cost of body structure.
Mass- reduction
impacts
• Body- in- white reduction: 170 lb ( 24%)
• Potential savings estimated be around 30% with mass- optimization
Status
• Conducted by Thyssen Krupp Stahl
• Called New Steel Body ®
• Engineering design study in 2004
Source • ThyssenKrupp, 2004. NewSteelBody: For a lighter automotive future.
Illustrations
Table 16. Summary of DaimlerChrysler Dodge Durango Next Generation Frame project
Mass- reduction
features
• Develop, build aluminum- steel hybrid frame, and design all- aluminum frame for sport utility vehicle
• Created a computer aided design ( CAE) model
• Evaluated impact on noise, vibration, and harshness ( NVH) and durability
• Completed CAE and design iterations for DaimlerChrysler 5- Star crashworthiness rating.
• Analyses “ satisfy all the DCX requirements for 5- Star crashworthiness, NVH, and durability.
• Assembled prototype frame into full – size vehicle and road tested
Mass- reduction
impacts
• Hybrid aluminum- steel frame reduction: 92 lb ( 30%)
• Designed aluminum frame reduction: ~ 140 lb ( 46%)
Status
• Developed by DaimlerChrysler and Pacific Northwest National Laboratory
• Also with Tower Automotive, Alcoa, Assured Design, Defiance, Mercia
• Designed and built 3 prototype frames for testing ~ 2005- 2006
Sources
• U. S. Department of Energy ( US DOE), 2006. “ Lightweight materials pave the road for energy- efficient
vehicles.” http:// www. eurekaalert. org/ features/ doe/ 2006- 06/ dnnl- limp062906. php. June 26. Accessed
March 20, 2010.
• U. S. Department of Energy ( US DOE), 2006. Progress Report for High Strength Weight Reduction
Materials. March.
• 21st Century Truck Partnership, 2006. Roadmap and Technical White Papers. 21CTP- 0003. December.
• 21st Century Truck Partnership, 2005. Transportation Materials Research and Development for Heavy
Vehicle Applications. Pacific Northwest National Laboratory. June 28.
Illustrations
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, 8 8 3 ) & % 3 ( % 0 1 2 % 9 ) , 4 ' % & 5 8 % & $ 4 & 5 6 : ; % $ # " + , " & $ % & ' $ % $ ( ( $ 9 & % 3 ( % ' / - ) 3 ( 3 ) * 5 6 : % 3 6 % & 5 8 % * $ 9 ' " 6 5 9 " + % 8 ) 3 8 $ ) & 5 $ 4 < %
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6 9 ) $ " 4 $ - % ( + $ $ & % ( , $ + % 9 3 6 4 , * 8 & 5 3 6 < % B ' $ %
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6 % ( 3 ) % & ' 5 4 % 9 + " 4 4 % 3 ( % # $ ' 5 9 + $ < %
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