DRAFT

COST-EFFECTIVENESS OF A 25% BODY AND CHASSIS 

WEIGHT-REDUCTION GOAL IN LIGHT-DUTY VEHICLES

Sujit Das

Energy and Transportation Science Division

Oak Ridge National Laboratory

Prepared for 

Lightweighting Materials

Office of Vehicle Technologies

U. S. Department of Energy

August 2008

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee 37831

managed and operated by

UT-Battelle, LLC

for the 

U.S. DEPARTMENT OF ENERGY

under contract No. DE-AC05-00OR22725
2

Cost-Effectiveness of a 25% Body and Chassis Weight-Reduction Goal 

in Light-Duty Vehicles

Oak Ridge National Laboratory

August 2008

1. Background

With the recent higher gasoline prices and new rules requiring automakers’ fleets to have 

average fuel economy of at least 35 mpg by 2020, the pressure to lightweight vehicles is 

stronger than ever before. Vehicle lightweighting represents one of several design 

approaches automakers are currently evaluating to improve fuel economy. 

Lightweighting is typically accomplished by downsizing, integrating parts and functions, 

substituting materials, or by combining these methods. Lightweighting Materials’ (LM’s) 

component of the U.S. Department of Energy’s Vehicle Technologies program focuses 

on the development and validation of advanced materials and manufacturing technologies 

to significantly reduce automotive passenger vehicle body and chassis weight without 

compromising other attributes such as safety, performance, recyclability, and cost. The 

specific goals of LM are to develop material and manufacturing technologies by 2010 

that, if implemented in high volume, could cost-effectively reduce the weight of 

passenger-vehicle body and chassis systems by 50% with safety, performance, and 

recyclability comparable to 2002 vehicles. In order to achieve this long-term weightreduction goal, LM has set annual intermediate weight-reduction goals, starting with 10% 

in FY2007, and finally achieving 50% by FY2010. This paper focuses on the 25% body

and chassis weight-reduction goal of FY2008, with emphasis on the assessment of costeffectiveness to achieve this desired goal.

To achieve its long-term weight-reduction goal, LM has prioritized its research areas in 

several lightweighting materials including advanced high-strength steel, aluminum, 

magnesium, titanium, and composites. Composites include metal-matrix materials and 

glass- and carbon-fiber reinforced thermosets and thermoplastics. Over the past several 

years, the LM R&D portfolio has included assessments of various lightweight body and 

front-end structures, such as those constructed of advanced high-strength steel, 

composite-intensive, and magnesium. These assessments, either completed or underway,

include, for example, one in which the goal is to design, analyze, and develop the 

technology for a composite-intensive, body-in-white structure that achieves a minimum 

of 60% weight savings over steel. Additionally, the latest LM multi-material vehicle 

(MMV) project aims to synthesize and demonstrate these various lightweight material 

component options in a single vehicle. Cost remains one of the major obstacles to

successful market penetration of these various lightweight materials. Today OEMs 

remain more focused on the vehicle’s retail price rather than on vehicle life cycle cost.

This paper provides an assessment of the cost-effectiveness of a 25% body and chassis 

weight-reduction goal for FY2008. The cost-effectiveness of the proposed weightreduction goal is determined based on the vehicle retail and life cycle cost analyses of 

scenarios of potential lightweight material substitution in various body and chassis 
3

components to achieve the desired weight-reduction goal. Cost methodology and 

potential data sources for the analysis are then discussed. Cost data collected for various 

vehicle components considered for achieving the weight reduction goal are then 

discussed, as are the assumptions and methodology used. A discussion of the results of 

the cost analysis of proposed scenarios is then presented, followed by conclusions.

2. Approach

2.1 Scenario Development 

Cost-effectiveness of a 25% body and chassis weight-reduction goal was demonstrated 

based on scenario analysis with each scenario focusing on a specific lightweight material 

type substitution at a major vehicle-component level. A representative mid-size vehicle, 

i.e. Honda Accord, was considered as the baseline against which the cost-effectiveness of 

scenarios was determined. Two plausible material scenario—one for aluminum and 

another for glass fiber-reinforced polymer-matrix composites (glass-FRPMCs)—have 

been developed with the focus on body and chassis applications. These two materials

have the potential to achieve the desired weight-reduction goal. Aluminum use in today’s 

light-duty vehicles is limited to about 325 lbs/vehicle, mainly in castings for the 

powertrain (engine block, cylinder head and transmission cases) and wheels, but 

aluminum use could be significantly greater with the addition of wrought aluminum that 

has a weight reduction potential range of 30-50% compared to conventional steel. GlassFRPMCs are used less than aluminum in today’s vehicle, and their application is limited 

to complex non-structural assemblies. Glass-FRPMCs offer a weight reduction potential 

of 20-35% compared to conventional steel.

Table 1 shows the two 25% body and chassis weight-reduction scenarios for a mid-size 

passenger car considered in the cost-effectiveness analysis. Each scenario focuses on a 

specific lightweight material option. This scenario approach allows determination of costeffectiveness at a vehicle level, the context important for the actual implementation and 

commercialization of the lightweighting materials technologies in the market place. Parts 

considered for the lightweight material substitution are based on their near-term market 

potential; the specific total number of parts considered under each scenario is dictated by

the material type and its weight reduction potential for achieving the overall body and 

chassis weight reduction goal. Specific components considered under body and chassis 

vehicle subsystems for both scenarios are highlighted in Table 1 (in bold type). The 

potential weight reduction for each part also is given. Since most lightweight component 

options considered here are yet to be commercialized, the percentage weight reduction 

assumed in each case is based on the best estimated value available in the literature today. 

The definitions of various vehicle components are based on the Automotive System Cost 

Model (ASCM, discussed below) and are provided in Appendix A. 
Table 1. Mid-Size 25% Body& Chassis Weight Reduction Scenarios1

SYSTEM

Baseline

Glass-FRPMC 

(25% Weight Reduction) Scenario

Aluminum 

(25% Weight Reduction) Scenario

Technology

Mass 

(kg) Technology

Mass 

(kg) Technology

Mass 

(kg)

Powertrain

Engine V-6 3.0L DOHC AL/AL 197 V-6 3.0L DOHC AL/AL 197 V-6 3.0L DOHC AL/AL 197

Energy Storage Lead-Acid, Standard 19 Lead-Acid, Standard 19 Lead-Acid, Standard 19

Fuel System Gasoline, 17 gal 83 Gasoline, 17 gal 83 Gasoline, 17 gal 83

Transmission Automatic (L5) 81 Automatic (L5) 81 Automatic (L5) 81

P/T Thermal Generic (car) 29 Generic (car) 29 Generic (car) 29

Driveshaft/Axle Generic 77 Generic 77 Generic 77

Differential Generic 25 Generic 25 Generic 25

Exhaust System Generic 48 Generic 48 Generic 48

Oil and Grease Generic 15 Generic 15 Generic 15

Powertrain Electronics Generic 10 Generic 10 Generic 10

Emission Control 

Electronics Generic 10 Generic 10 Generic 10

Body

Body-in-White Midsize steel unibody 320 Glass Fiber TS/Composite (30% wt redn.) 232 Aluminum Unibody (40% wt redn.) 176

Panels Stamped Steel 60 Glass Fiber TS/Composite (25% wt redn.) 39 Stamped Aluminum (40% wt redn.) 36

Front/Rear Bumpers Sheet Steel 10 Stamped Aluminum (40% wt redn.) 6 Stamped Aluminum (40% wt redn.) 6

Glass Conventional, 4 mm 40 Conventional, 4 mm 40 Conventional, 4 mm 40

Paint Solventborne, avg color 12 Solventborne, avg color 12 Solventborne, avg color 12

Exterior Trim Generic 10 ULSAB (35% wt reduction) 6.5 Generic 10

Body Hardware Generic 10 Generic 10 Generic 10

Body Sealers and 

Deadners Generic 2 Generic 2 Generic 2

Chassis

Cradle Generic 35 Cast Aluminum (45% wt redn.) 19 Generic 35

 

1All weights in the table denote values after primary weight savings only.
5

SYSTEM

Baseline

Glass-FRPMC 

(25% Weight Reduction) Scenario

Aluminum 

(25% Weight Reduction) Scenario

Technology

Mass 

(kg) Technology

Mass 

(kg) Technology

Mass 

(kg)

Corner Suspension Generic 47 Aluminum (35% wt. reduction) 31 Generic 47

Braking System ABS 48 Aluminum (5.5% wt. reduction) 45 ABS 48

Wheels and Tires Aluminum 15” 71 Aluminum 15" – Forged (11% wt. redn.) 63 Aluminum 15” 71

Steering System Generic 27 Aluminum (5.5% wt. reduction) 26 Generic 27

Interior

Instrument Panel Generic 26 Generic 26 Generic 26

Trim and Insulation Generic 24 Generic 24 Generic 24

Door Modules Generic 28 Generic 28 Generic 28

Seating and Restraints Generic 66 Generic 66 Generic 66

HVAC Generic 22 Generic 22 Generic 22

Electrical 33 33 33

Final Assembly 40 40 40

Total Body & Chassis 

Weight

(% less than baseline)

692 523

(25%)

520

(25%)

Total Vehicle Weight 1525 1356 1353

Table 1. Lightweighting Options Considered for Various Body & Chassis Components

Under Two Lightweight Material Scenarios
2.1.1 Aluminum

Aluminum unibody structure and panels have been considered under the aluminum 

scenario, although most applications to date—as in the Audi A2 and A8 and the 

Chevrolet Corvette C6 Z06—have been an aluminum spaceframe structure achieving 

weight savings in the range of 30-40%. Unibody architecture is currently being used in 

the Jaguar XJ8, and it favors higher volumes with lower variable costs. The tradeoff is 

the expense of higher investment costs due to expensive stamping dies. Under simple 

load cases (e.g., bending stiffness and three-point bending), aluminum use can provide up 

to 50%-60% mass reduction at the expense of 40% more package space compared to 

steel. But, in actual vehicle body structures, where load cases are much more complex, 

actual reductions obtained are lower and depend on whether they are compared to 

optimized steel design (such as ultra light steel autobody) or the conventional nonoptimized steel design. Recent study by Aluminum Association on the use of aluminum 

structures in conjunction with alternative powertrain structures in automobiles indicates a 

weight savings potential of 47% over the steel baseline—similar to the value obtained in 

Ford’s aluminum intensive concept vehicles, the Ford Taurus 1997, an effort initiated in 

late 1990s (Aluminum Association 2008). A lower weight reduction potential of 45% has 

been used in our analysis in order to achieve the overall body and chassis weight 

reduction goal. A 40% weight reduction assumption for closure panels is consistent with 

the recent Aluminum Association design and the latest estimate (Montalbo et al. 2008).

Besides body structure and closure panels, aluminum substitution of front and rear 

bumpers has been included to achieve the desired total 25% primary weight savings goal. 

Bumpers are a good example of a successful aluminum bolt-on high volume application.

2.1.2 Glass-FRPMC

Application of glass-FRPMC in automobiles is quite limited and occurs only in lowvolume niche vehicles today such as Chevy Corvette, Dodge Viper, and Cadillac XLR. 

The highest volume of composites use in Class A exterior applications is in the fascia 

systems. Similarly, exterior non-class A composites use is currently limited to a select 

few applications such as pickup truck box inner panels, removable roofs, gate panels, 

running boards, truck enclosures, wheel housings, and underbody panels. The very few 

limited structural composites applications today are radiator supports, bumper beams, 

skid plates, and grille opening reinforcements. Consideration of glass-FRPMC in our 

analysis was mainly limited to body applications that have the most total weight 

reduction potential. A weight reduction potential of 30% compared to steel was assumed,

compared to 25% value reported for reinforced reaction injection molded polyurea/glass 

flake body structure (Dieffenbach and Mascarin 1993). However, for glass-FRPMC 

panels, a 25% weight reduction was assumed consistent with the available estimates. 

Recent results of the United States Automotive Materials Partnership (USAMP) Multi-Material 

Vehicle (MMV) project on the composite underbody has considered several glass-fiber 

reinforced polymer options providing a weight savings potential of 7-40% compared to 

the steel baseline, the upper limit of reduction available when glass-fiber fabric with 

cores is used (DOE 2008). However, when considered on the basis of functional 

equivalence (with the consideration of reinforcement brackets and rails) to steel in 
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addition to the stiffness and crashworthiness requirements, the weight savings potential 

was estimated to be around 20% with random glass fibers with core. It is most likely that 

the assumed body weight reduction potential of body-in-white structure in our case is on 

the high side based on the applications seen in the marketplace so far.

Due to lower weight reduction potential of glass-FRPMC compared to aluminum, the 

glass-FRPMC scenario includes the use of aluminum in several vehicle body and chassis 

components to achieve the desired body and chassis weight reduction goal. Aluminum 

has been considered for front/rear bumpers, corner suspension, cradle, braking system, 

steering system, and wheels and tires. Aluminum (forged or cast) is desirable in vehicle 

chassis components since it reduces un-sprung weight of the suspension, thereby

improving overall handling performance and ride comfort. Weight reduction for the 

cradle has been assumed to be higher than for front/rear bumpers, i.e., 45% vs. 40%. 

Aluminum penetration has been relatively high in steering knuckles, and a weight 

reduction in the range of 35-45% can be achieved by integrating multiple parts into a 

single unit. Similarly, aluminum control arms have a market share of 20% today, with a 

weight reduction potential of 20-30% compared to steel. Aluminum corner suspension 

substitution assumes here both aluminum control arms and steering knuckles, with a 

combined weight reduction potential 35%.

Aluminum use has been considered for brake actuators and steering wheel column, with 

an estimated weight savings potential of 30.5% and 43%, respectively (EEA 2007). 

However, in both cases, the substitution of a single component in the system achieves a 

relatively small weight reduction at the system level compared to the weight reduction of 

the part alone. The overall weight reduction potential is assumed to be 5.5%. Although

the wheels segment has seen consistent growth in aluminum use, it is anticipated that 

there will be shift from cast wheels to forged wheels without any overall huge percentage 

market gains in the future. Forged wheels considered here for wheels and tires are 

estimated to provide an additional 11% weight savings compared to cast aluminum 

wheels. In order to achieve the total around 25% primary body and chassis weight 

savings goal, a 35% reduction in exterior trim weight has been assumed. This weight 

savings is consistent with the target weight for the PNGV-Class vehicle which has a 

target weight of around 203 kg body structure (ULSAB-AVC 1999).

2.1.3 Secondary Weight Savings

The objective for the selection of lightweighting material options for various vehicle 

components (as discussed above) was to achieve the primary 25% body and chassis 

weight-reduction goal. However, consideration of secondary weight savings in body and 

chassis components is important because it takes into account the effect of primary

savings on the powertrain, chassis, and body components. Powertrain resizing in 

secondary weight savings calculations allows comparisons of functionally equivalent 

vehicle designs—a reduced vehicle weight requires a less powerful engine to achieve 

equivalent performance (i.e., acceleration, range etc.). Secondary weight savings have 

been estimated by ASCM and those related to the two scenarios considered here are 

presented in Table 2, along with other estimated major parameters in the cost-
8

effectiveness analysis. Although the primary weight savings in both lightweight material 

scenarios are roughly the same, the total secondary weight savings obtained is different 

because of different components considered for primary weight savings. Total secondary

weight savings is estimated to be 70% and 44% of primary savings for aluminum and 

glass-FRPMC lightweight material scenarios, respectively. The aluminum scenario 

achieves a higher percentage of secondary weight savings because the substitutions are 

limited to body components, whereas the glass-FRPMC scenario includes both body and 

chassis components. Most estimated secondary weight savings occur in the powertrain 

system under both scenarios. Absolute secondary weight savings is less in the case of 

glass-FRPMC since primary weight savings resulted in lower chassis component weight 

although the percentage secondary weight reduction value used per component has been 

the same as the other scenario. Total estimated secondary weight savings depend on the 

extent of powertrain downsizing assumed and also the total number of vehicle 

components considered. Since secondary weight savings is limited to only major vehicle 

components in ASCM (i.e., all chassis components and a few major powertrain and body

components), the percentage total weight savings in this case is somewhat lower than 

another recent estimate (Malen and Reddy 2007).

Note: % values within parenthesis indicate w.r.t. baseline steel

With the consideration of secondary weight savings, total body & chassis weight savings 

is estimated to be 31.6% and 26.1% for aluminum and glass-FRPMC scenarios, 

respectively, higher than the 25% primary weight reduction goal as shown in Table 2. 

There will be a decrease in powertrain weight with powertrain resizing, where engine 

power is estimated to decrease by 14%. The resulting percentage vehicle weight 

reduction for the corresponding scenarios has been estimated to 19% and 16%, 

Table 2. Estimated Major Parameters Considered for Cost-effectiveness of 25% 

Body and Chassis Weight Reduction Goal

Parameter Baseline

25% Body and Chassis Weight Reduction 

Scenario

Aluminum Glass-FRPMC

Primary Body & Chassis 

Weight Savings

NA 172 kg (25%) 169 kg (25%)

Secondary Weight 

Savings

Body & Chassis NA 46 kg (6.6%) 11 kg (1.6%)

Powertrain NA 74 kg 63 kg

Total NA 120 kg 74 kg

Body & Chassis Weight 692 kg 475 kg (31.6%) 511 kg (26.1%)

Powertrain Weight 594 kg 520 kg (12.5%) 531 kg (10.6%)

Engine Power 122 kW 102 kW 105 kW

Final Vehicle Weight 1524 kg 1235 kg (19%) 1281 kg (16%)

Combined Fuel Economy 23 mpg 25.9 mpg 25.5 mpg

Vehicle Lifetime 

Operation

120,000 miles
9

respectively. Fuel economy estimates have been based on a reasonable rule of thumb that 

each one percent reduction in weight should give a 0.66 percent improvement in fuel 

economy, after a vehicle has been fully redesigned to account for the reduced power 

demands of a lower mass. Combined vehicle fuel economy would increase from the 

baseline value of 23 mpg to 25.9 mpg and 25.5 mpg for aluminum and glass-FRPMC 

scenarios, respectively, with the 25% body and chassis weight-reduction goal. Total 

vehicle operation lifetime is assumed to be 120,000 miles based on average annual miles 

driven and vehicle life as 10,000 and 12 years, respectively.

2.2 Cost Estimation Methodology

The cost-effectiveness of the 25% body and chassis weight-reduction goal was estimated 

using the Automotive System Cost Model (ASCM), developed jointly by Oak Ridge 

National Laboratory and Ibis Associates, Inc. in collaboration with Argonne National 

Laboratory. ASCM estimates the vehicle-manufacturing cost at a level of five major 

vehicle subsystems (powertrain, chassis, body, interior, and electrical) consisting of more 

than thirty-five components based on the aggregation of several components under the 

definition of Uniform Parts Grouping (UPG) generally used by the automotive industry

(as listed and defined in Table 1 & Appendix A). Each component represents a specific 

manufacturing technology. Vehicle retail price based on the sum of manufacturing cost 

(i.e., costs of components and assembly), overhead, and selling is added to vehicle 

operation costs for the vehicle life cycle cost estimation. The interrelationships among 

vehicle subsystems and their effect on vehicle manufacturing cost are addressed, allowing 

inclusion of the impacts of secondary mass and cost savings as well. Functional 

interrelationships have been developed for major chassis components to estimate 

secondary mass savings based on first principles of physics, and using semi-empirical 

and empirical information available from the literature today. The powertrain sizing 

routine in this model is based on the algorithm used in the Argonne National 

Laboraotry’s (ANL) hybrid vehicle cost model (HEVCOST), where the power and mass 

projections of various powertrain components are based on component-specific power 

and efficiency values, with the capability to evaluate alternative hybrid electric vehicle 

configurations and performance strategies (Plotkin et al. 2001). The main objective of 

this model is to facilitate estimation of vehicle-manufacturing and life-cycle costs using a 

uniform methodology to allow comparison of alternative technologies being considered 

for advanced technology vehicles today. This cost model has been recently integrated 

into the vehicle performance model PSAT (Powertrain System Analysis Toolkit) 

developed by Argonne National Laboratory, thereby facilitating instantaneous vehicle 

cost estimation based on the detailed powertrain component sizing estimates by PSAT. 

This cost model has been used in several studies for a comparative cost assessment of 

different powertrain and body-in-white options for advanced technology vehicles (Das

2004 and 2005; Rousseau et al. 2005).

Two types of overhead, i.e., OEM and dealer margin are added to the vehicle 

manufacturing cost to estimate vehicle retail price. The former is assumed to be fixed, 

while the latter varied with the vehicle manufacturing cost. Vehicle operation cost 

categories considered in the vehicle life cycle cost estimation include financing, 
10

insurance, local fees, fuel, battery replacement, maintenance, repair, and disposal. 

Financing, insurance, and local fees costs are dictated by the vehicle retail price, and so is 

the fuel cost by fuel economy (estimates are shown in Table 2) and an assumed gasoline

price of $4/gallon in this analysis. With the exception of maintenance and repair, all other 

operation cost categories vary with the two lightweighting scenarios considered here

based on estimated vehicle retail price and fuel economy. Total life cycle cost is 

estimated as the net present value assuming a vehicle life of 12 years, 120,000 vehicle 

lifetime operation miles, and a discount rate of 10%.

2.3 Component Cost Data

Component technology cost data as highlighted by bold letters under the two scenarios in 

Table 1 were collected mainly based on the latest estimates developed by Ibis Associates, 

Inc. using results of the recent studies developed for the industry (Ibis 2008). For 

example, both the Aluminum Association and USAMP have recently been involved in 

the detailed cost analysis of aluminum and glass-FRPMC body structures, respectively. 

For other lightweight component technology costs considered here, where detailed 

analyses were unavailable, existing Ibis cost models developed for the relevant materials 

systems were used to estimate the component costs. Cost data for other components—

those for which the technology remained unchanged—were the same as those in the 

original model, since our objective in this analysis is to determine the relative costeffectiveness of these two lightweight scenarios and not the absolute total vehicle cost.

Note that component technology costs in ASCM are based on OEM costs and represented 

in terms of functional relationships such as component mass and power, derived based on 

the detailed cost analyses available in the literature.

The cost estimate of the aluminum unibody structure is based on the latest detailed 

evaluation by the Aluminum Association, which has reconsidered the manufacturing 

economics of the original P2000 program with updated practices and materials pricing 

(Aluminum Association 2008). The aluminum structure was 47% lighter than the steel 

baseline on the basis of weight distribution assumptions of 94% aluminum stampings, 3% 

aluminum castings, and 3% mild steel stampings, at a 30% cost premium. Based on the 

regression analysis of multiple scenarios results, cost relationships of structure, panel, and 

assembly have been developed separately as a function of part mass, material price, part 

count, part area, and annual production volume which were then used in the analysis 

here.

Recent cost estimates of the underbody for a luxury rear-drive vehicle developed by Ibis 

Associates, Inc. considered under the USAMP MMV project were used for the 

development of cost relationships for glass-FRPMC body components. Several 

combinations of fiber type (glass vs. carbon) and form (random vs. fabric) and 

manufacturing technologies were considered under that project. Specific material masses 

both in terms of absolute values and relative weight fractions for underbody were based 

on the detailed design effort. Among several competing molding technologies considered

under this project, cost data for compression of sheet molding compound was used for the 

analysis here. The sheet molding compound was modeled as a separate operation by
11

molders, either as a profit center for companies with internal compounding or as a 

material purchased from a separate company. Random glass fiber with core and vinyl 

ester as the matrix material were used where composites contributed 57% to the overall 

part weight. In order to extend the composite underbody results to the entire structure, the 

equivalent description of components comprising the floor and rails in the baseline steel 

BIW was examined, and the overall underbody was calculated to be 29% of the mass and 

25% of the cost of the entire structure. Cost relationships thus developed reflect the latest 

pricing information and molding processing technology.

Figure 1 shows the estimated cost sensitivity to annual production volume of three types 

of body-in-white structures considered in this analysis. The cost of body-in-white 

structure includes the assembly cost. Cost graphs shown here are based on the baseline 

weight for a mid-size vehicle considered in the model and not the actual weight used in 

the analysis here. For example, baseline masses of body-in-white structure considered for 

steel, aluminum, and thermoset/glass composites (TS/glass composites) are 250 kg, 143 

kg, and 202 kg, respectively. Based on the current material pricing (i.e., steel at $0.77/kg 

aluminum sheet at $3.31/kg, aluminum casting at $2.86/kg, vinyl ester compound at

$4.24/kg, and glass fiber at $1.50/kg) and masses assumed, the aluminum unibody

structure is always more expensive than steel, whereas TS/glass composites are 

competitive at annual production volume up to 60,000 parts. Most past studies indicate a 

lower production volume for cross-over point for the cost-effectiveness of TS/glass 

composites, yet a recent study shows glass-reinforced body-in-white structure can be 

cost-effective at an annual production volume up to 105,000, which represents 68% of 

car models and 29% of all cars produced in North America in 2005 (Fuchs 2008). The 

cost sensitivities of steel and aluminum structures are quite similar to each other in terms 

of the curve slope, but they are offset by the material price difference and some increased 

processing costs. As also has been observed earlier, the cost sensitivity curve for glass0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 25 50 75 100 125 150 175 200 225 250 275 300

Annual Production Volume (K)

B

ody-In-White Structure C

ost ($/part)

Steel Unibody

Aluminum Unibody

TS/Glass Composite

Figure 1. Lightweight Material Body-In-White Cost Sensitivity to

Annual Production Volume
12

FRPMC body structure is relatively flat compared to other materials. For our analysis, the 

threshold production volume of cost-effectiveness has been considered, 240K parts/year 

for both baseline steel and aluminum, whereas 60K parts/year for glass-FRPMC.

Figure 2 shows the part cost sensitivity to aluminum casting price for four different 

aluminum chassis components considered under the glass-FRPMC scenario based on part 

weight used in a mid-size vehicle. Note that part cost estimates under the assumed base 

material price for the comparative scenario analysis here are also shown in this figure. 

Cost relationships for aluminum cradle and forged aluminum wheels include not only

casting cost, but also melting, scrap recovery, machining, and corrosion protection. Cost 

of forged aluminum wheels are based on 15” wheels and reflects current material pricing 

and processing technology improvements and also includes tire costs. Cost estimates of 

aluminum braking and steering systems were made by adding the estimated cost of 

replaced aluminum component (e.g., brake actuators and steering wheel column for 

braking and steering systems, respectively) to the unchanged original balance of system 

cost made of conventional steel. Cost data of replaced aluminum components are based 

on the recent available estimate (EEA 2007). Cost relationships consist of two 

components, i.e., material and processing. As Figure 2 shows, forged aluminum wheels 

have a higher processing cost component than for cast aluminum cradles. Higher weight 

of corner suspension causes its cost to be higher and more sensitive than the chassis to 

aluminum ingot price. The material price cost sensitivity of steering and braking system 

cost is not that high since aluminum component in each case contributes to less than 10% 

of total system weight.

0

100

200

300

400

500

600

700

800

0.5 1 1.5 2 2.5 3 3.5 4 4.5

Al Casting Price ($/kg)

Part Cost ($)

Brake System

Wheels & Tires

Steering System

Chassis 

Corner Suspension 

 Base Price $2.86/kg

Figure 2. Aluminum Chassis Component Cost Sensitivity to Material Price
13

3.0 Results

Figure 3 shows the cost savings for the two scenarios compared to the baseline, by major 

vehicle systems, vehicle retail price, and life cycle cost. Only three major vehicle system 

cost savings have been considered in this figure as defined in ASCM and listed in Table 

1, since other system costs (i.e., interior, electrical, and final assembly) have been 

assumed to be the same under all scenarios. Vehicle retail price would increase by about 

$180/vehicle under the aluminum scenario, however there would be about $1100/vehicle 

cost savings in terms of life cycle cost. The increase in vehicle retail price is mainly due 

to the body system cost increase of about $1000, the result of the higher cost of 

aluminum body structure. The cost savings due to the downsizing of the powertrain and 

chassis is not sufficient to lower the vehicle retail price. It is estimated that if the price of 

aluminum sheet used in the body structure and panels is reduced from the baseline price 

of $3.31/kg to $2.95/kg, the cost-effectiveness at the vehicle retail price could then be

achievable. The improved fuel economy under the aluminum scenario lowers fuel costs

significantly—enough to offset small increases in the small increase in vehicle retail 

price—to result in an overall total lower vehicle life cycle cost.

-1500

-1000

-500

0

500

1000

1500

2000

Aluminum Glass-FRPMC

C

ost Savings ($/vehicle)

Pow ertrain

Body

Chassis

Vehicle Retail Price

Operation

Life Cycle Cost

Figure 3. Estimated Cost Savings of Two Lightweight Material Vehicle Scenarios
14

The glass-FRPMC on the other hand is cost-effective based on both vehicle retail price 

and life cycle cost. The increase in vehicle body system cost is not as high as in the case 

of aluminum scenario (i.e., about $400/vehicle compared to $1000/vehicle for 

aluminum), since as discussed earlier under and shown in Figure 1 that the cost of 

aluminum body structure is more expensive than thermoset glass-FRPMC structure at all 

annual production volumes. Powertrain system and chassis system cost savings are lower 

in the glass-FRPMC scenarios because the overall vehicle weight reduction is less than in 

the aluminum scenario, the difference being less secondary weight savings for glassFRPMC. Higher aluminum price has also contributed to lower chassis system cost 

savings in this case. Cost savings in terms of vehicle retail price and life cycle cost are 

estimated to be about $280 and $1600, respectively. Vehicle life cycle cost savings is 

higher in this case not only due to vehicle retail price savings but also because costs 

incurred in some of the operation cost categories such as financing, insurance, and local 

fees, are reduced.

4.0 Conclusions

Cost-effectiveness of ALM’s 2008 body and chassis weight reduction goal of 25% in 

light-duty vehicles was assessed based on the use of lightweight material options for 

various body and chassis components under two plausible mid-size vehicle scenarios, 

each scenario focusing on a specific lightweight material option, i.e., aluminum or glassFRPMC. Lightweight material substitution options considered here focused on under 

body systems; but additional chassis components for substitution were also selected for 

the glass-FRPMC scenario to achieve the desired overall weight reduction goal. The 

analysis also considers the effect of primary weight savings of 25% on other vehicle 

components that can be resized while maintaining the same level of vehicle performance 

with the reduced vehicle weigh. This weight savings is known as secondary weight 

savings. Estimated secondary weight savings varied between the two scenarios because 

of the difference in consideration of total number and type of components for primary

weight savings. Due to consideration of secondary weight savings, total body and chassis 

weight savings is estimated to be in the range of 27-32%, whereas final vehicle weight 

savings of 16-19%. Cost-effectiveness of 25% body and chassis weight reduction goal is 

estimated in terms of both vehicle retail price and life cycle cost using the detailed 35+ 

component level automotive system cost model developed by ORNL and Ibis Associates, 

Inc. Cost data of components considered for lightweight material substitution are 

collected from the recently completed major studies, thereby reflecting the latest 

technology developments and material prices.

Because of the consideration of powertrain resizing and secondary body and chassis mass 

savings, both lightweight material vehicle options are cost-effective in meeting the ALM 

25% body and chassis weight savings goal from the life cycle cost perspective. Use of 

lightweighting materials such as aluminum and glass-FRPMC would be sufficient to 

achieve the goal but cost-effectiveness needs to be considered beyond just the 

component-to-component material substitution and vehicle retail price basis.

Consideration of secondary weight savings and vehicle life cycle cost perspectives are 

important when considering the economic viability of lightweighting vehicles. Among 

the two lightweight material options considered, glass-FRPMC appears to be more cost-
15

effective since the cost of body structure of aluminum is still high today even with the 

consideration of latest technology developments and material pricing. In the case of 

aluminum scenario, the vehicle retail price would be about be $180 higher; a reduction in 

aluminum sheet price to a value of about less than $3.00/lb would improve its 

competiveness at the vehicle retail price level. Because of the consideration of secondary

mass savings, the cost penalty due to lightweighting vehicles has been found to be more 

favorable than those reported earlier in the literature. Since the cost penalty for the use of 

lightweight body structure estimated to be in the range of $400-$1000/vehicle under two 

scenarios when not accounting for secondary mass savings, it is likely that a significantly

higher fuel price would be necessary if the cost-effectiveness without secondary mass 

savings effect needs to be achieved on a life cycle cost perspective at least for the high 

end of body structure cost penalty case. 

Findings in this analysis are consistent with the latest findings by the Aluminum 

Association although complete secondary mass savings have not been taken into 

consideration in vehicle life cycle cost comparisons (Aluminum Association 2008). The 

aluminum body structure and panels using the conventional powertrain have been found 

to be the most cost-effective option with the consideration of powertrain resizing and

other subsystems’ weight savings. Furthermore, aluminum vehicles with conventional 

powertrain offer the least cost on the basis of combined powertrain and body structure 

cost at $44 per mpg change with a 10% mpg improvement but a lower life cycle cost 

among the various advanced vehicle technology options considered in that study. Vehicle 

platforming considerations which allow low annual production volume would facilitate 

the competitiveness of glass-FRPMC body structure as also has been noted in the latest 

study (Fuchs (2008). Lightweighting also improves the cost-effectivenesss of advanced 

technology vehicles by lowering the expensive powertrain cost while maintaining the 

performance (Aluminum Assocation (2008) and Das (2005)). Consideration of 

powertrain resizing, secondary mass savings, and life cycle cost perspectives would 

therefore be important to maximize the fuel economy gains from a lightweight structure 

and eventual successful market penetration of lightweight vehicles in the future.
16

REFERENCES

Aluminum Association (2008). “Aluminum Vehicle Structure: Manufacturing and 

Lifecycle Cost Analysis: Hybrid Drive and Diesel Fuel Vehicles,” Research Report 

No. 2008-05, written by Ibis Associates, Inc. for the Aluminum Association.

American Iron and Steel Institute (AISI) (2001). “UltraLight Steel Auto Suspension: 

Engineering Report,” Washington, DC, Dec.

Bull, M. (2008). Novelis, Inc. Detroit, MI. Personal communication with Sujit Das, Oak 

Ridge National Laboratory, Oak Ridge, TN, Feb. 19.

Das, S. (2004). “A Comparative Assessment of Alternative Powertrians and Body-inWhite Materials for Advanced Technology Vehicles,” SAE Paper No. 2004-01-0573, 

the Society of Automotive Engineers, Warrendale, PA.

Das, S. (2005). “Lightweight Opportunities for Fuel Cell Vehicles,” SAE paper no. 2005-

01-0007, the Society of Automotive Engineers, Warrendale, PA.

Dieffenbach, J. R. and Mascarin, A. E. (1993). “Body-in-White Material Systems: A 

Life-Cycle Cost Comparison,” Journal of Metals, Vol. 45, No. 6, pp. 16-19, June.

Energy and Environmental Analysis, Inc. (EEA) (2007). “Analysis of Light-Duty Vehicle 

Weight Reduction Potential,” draft final report submitted to the U.S. Department of 

Energy, Office of Policy, Arlington, VA, July.

Fuchs, E. R. H. Field, F. R. Roth, R. and Kirchain, R. E. (2008). “Strategic Materials 

Selection in the Automobile Body: Economic Opportunities for Polymer Composite 

Design,” Composites Science and Technology, Vol. 68, pp. 1989-2002.

Ibis Associates, Inc. (Ibis) (2008). “Data Document: ORNL Automotive System Cost 

Model,” Waltham, MA, July 1.

Malen, D. E. and Reddy, K. (2007). “Preliminary Vehicle Mass Estimation Using 

Empirical Subsystem Influence Coefficients,” report prepared for the FGPC Mass 

Compounding Project Team, Auto/Steel Partnership, Southfield, MI, May 9.

Montalbo, T. Roth, R. Kirchain, R. and Lee, T. M. (2008). “Modeling Costs and Fuel 

Economy Benefits of Lightweighting Vehicle Closure Panels,” SAE Paper No. 2008 

01-0379, the Society of Automotive Engineers, Warrendale, PA.

Plotkin, S. et al. (2001). “Hybrid Vehicle Technology Assessment: Methodology, 

Analytical Issues, and Interim Results,” Argonne National Laboratory Report 

ANL/ESD/02-2, Argonne, IL.
17

Rousseau, A. Sharer, P. and Das, S. (2005). “Trade-off between Fuel Economy and Cost 

for Advanced Vehicle Configurations,” presented and published at EVS21conference, 

held in Monaco, Apr. 2-5.

U.S. Department of Energy (DOE) (2008). “Automotive Composites Consortium Focal 

Project 4,” Automotive Lightweighitng Materials: FY 2007 Progress Report, 

Washington, DC.

Ultra light Steel Autobody – Advanced Vehicle Concepts (ULSAB-AVC) (1999). 

“Description of ULSAB-AVC Benchmarking and Target Setting,” Southfield, MI. 

Nov. 18.
18

Appendix A

ASCM Vehicle Component Definition

ASCM UPG ASCM Description

Group Name

Powertrain Engine 30A Base Engine In this model, 'engine' refers to conventional heat 

engines. In addition to basic powerplant and auxiliary 

systems and components, engine cooling systems, 

lubrication, fluid containers and pumps are also included.

30B Other Engine 

Components

Fuel Cell n/a Fuel Cell Power System

Generator n/a The APU or power converter for parallel and series 

hybrids.

Motor n/a The electric motor, including power cables.

Controller/

Inverter

n/a The power controller/phase inverter system

Energy 

Storage

36K01 High Voltage 

Battery

The primary electrical energy storage device or package. 

Maybe a single battery or module of linked cells.

Fuel System 36F Fuel Tank and 

Lines

Fuel tank, gauge, tank shield, access door, mounting 

straps, fuel pump.

37B Fuel 

Transmission 36E G Transmission In this model the transmission refers to the gearbox only. 

Note that in some literature, "transmission" refers to the 

clutch, gearbox, driveshaft, and differential. These are 

each treated as separate components/subsystems in this 

model.

36C Clutch and 

Controls

Supplied as a single assembly, a releasable coupling that 

transmits torque from the engine to gearbox.

Driveshaft/

Axle

31 Final Drive A single assembly that couples with the gearbox and 

differential

31 Final Drive An assembly of the axle shaft, housing, boots, and 

couplings to the wheels

Differential 31 Final Drive Transmits energy from driveshaft to axles and allows for 

differential speed of each wheel.

P/T Thermal Cooling module (radiator, fan assembly etc)

Exhaust 

System

36E

36O

Exhaust System

Catalytic 

Converter

All exhaust equipment after the manifold; pipe: catalytic 

converter, muffler.

Powertrain 

Electrical

30C Engine Electrical Engine control wiring, sensors and processors. The 

controller for electric motors for HEVs may be considered 

as part of the electric motor, or could be included here, if 

desired. Low voltage used for accessory power is also 

included here.

Emission 

Control 

Electronics 30C10

Engine Emission 

Controls

The sensors, processors, and engine feedback 

equipment that maintain emissions within specified 

parameters.

Oil and 

Grease

37B Oil and Grease Engine oil, transmission oil, miscellaneous lubricants
19

ASCM UPG ASCM Description

Group Name

Body BIW 11A-11B Body in White and 

closures

The Body-In-White is the primary vehicle structure, 

usually a single-body assembly, consisting of engine 

compartment, passenger cabin, and storage. Closure 

panels (including hinge mechanism) and hang-on panels 

(such as fenders) are included, even if non-structural. In 

this model, doors are included as well.

Front/Rear 

Bumper

36G Fenders

Glass 18 Glass Front and rear windshields, door window glazing

Paint

22 Paint and Coating Includes the cost and mass of the total painting operation; 

e-coat, priming, base coats, color coats, clear coats.

37A, C, D Paint

Exterior 

Trim

14, 20 Molding and 

Ornaments

Bumper cover, air deflectors, ground effects, side trim, 

mirror assemblies, nameplates

Body 

Hardware

Door window mechanism, wipe/wash, defog/deice, door 

latch mechanism

Body 

Sealers & 

Deadeners

Self-explanatory

Chassis Cradle 32 Frame A front sub frame that bolts to the BIW and supports the 

mounting of the engine

Corner 

Suspension

33 Suspension Upper and lower control arms, ball joints, spring, shock 

absorber, steering knuckle, stabilizer shaft

Braking 

System

35 35D Brakes Hub, disc, bearings, splash shield, and calipers.

Wheels and 

Tires

36A 36C Wheels, Tires, and 

Tools

Self explanatory. Tools determinant by type of tires 

featured.

Steering 

System

34 Steering A complex system from the steering wheel, column, 

joints, linkages, bushes, housings and potentially 

hydraulic or electric assist equipment.

Interior Instrument 

Panel

21 Trim and 

Insulation

The instrument panel module consists of an underlying 

panel structure, knee bolsters and brackets, the 

instrument cluster, exterior surface, wiring, console 

storage, glove box panels, glove box assembly and 

exterior, and a top cover.

Trim and 

Insulation

15,17,21 Headliner Headliner is actually the overhead system containing 

acoustical sound absorption, assist handles, coat hooks, 

modular headliner assemblies, overhead console 

assemblies, small item overhead storage, pillar trim, sun 

visors and retainer.

Center Console Emergency brake cover, switch panels, ash trays, arm 

rest, cup holders, sometimes grouped with seating.

Package Tray A molded or formed panel behind the rear seat, 

sometimes contains accessory brake light.

Carpeting/Flooring Acoustical sound absorption; padding and carpet, 

insulation and accessory mats sometimes flooring may be 

sold as part of a combined acoustic package, also 

involving other sound abatement components, such as 

wheel well liners and under hood insulation

Door 

Modules

19 Convenience 

Items

A door panel system containing door insulation, door trim 

assemblies/panels, map pocket trim, cup holders, ash 

trays, seatbelt retractor covers, speaker grills, armrests, 

switch panels and handles

Seatbelt & 

Restraints

16 Seats The seating system contains seat tracks, seat frames, 

foam, trim, map pockets, restraint anchors, head restraint, 
20

ASCM UPG ASCM Description

Group Name

and armrests.

81 Safety Equipment Seat belts, tensioners, clips, air bags and sensors 

assemblies

HVAC 80A, B Air Conditioning 

System

Condenser, heater, ducting, and controls, compressor 

and A/C hardware.

80H, J Heating System

80K, M, C Other Climate 

Control

Electrical Interior 

Electrical

12F-13, 79 Electrical 

Components

Wiring and controls for interior lighting, instrumentation, 

and power accessories, entertainment system.

85 Accessories 

Equipment

Chassis 

Electrical

36K Chassis Electrical ABS electrical system (wiring, sensors, processors), 

traction control

Exterior 

Electrical

14,20 Molding and 

Ornaments

Head lamps, fog lamps, turn signals, side markers, tail 

light assemblies

Final 

Assembly

Interior

Chassis

Powertrain

Electronics

Other 

Systems

Final assembly of vehicle components is represented at 

the level of five major vehicle subsystems under which 

components are grouped