Document ID: EPA-HQ-OAR-2010-0162-3492
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-08-29T04:00Z

DRAFT

COST-EFFECTIVENESS OF A 40% BODY AND CHASSIS WEIGHT-REDUCTION GOAL IN
LIGHT-DUTY VEHICLES

Sujit Das

Energy and Transportation Science Division

Oak Ridge National Laboratory

Prepared for 

Lightweight Materials

Office of Vehicle Technologies

U. S. Department of Energy

June 2009

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

Cost-Effectiveness of a 40% Body and Chassis Weight-Reduction Goal 

in Light-Duty Vehicles

Oak Ridge National Laboratory

June 2009

1.  Background

With the recent higher gasoline prices, new emission and fuel economy
regulations that require by 2016 a 30% reduction in CO2 and other
emissions and an average fuel economy of at least 35 mpg, the pressure
to lightweight vehicles is stronger than ever before. The next few years
will see considerable light-weighting across the automotive industry.
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 weight-reduction goal, LM has set annual
intermediate weight-reduction goals, starting with 10% in FY2007, and
finally achieving 50% by FY2010. This paper is a follow-on to an earlier
study which focused on the 25% body and chassis weight-reduction goal of
FY2008 (Das 2008). The present study emphasizes the assessment of
cost-effectiveness to achieve the desired goal of 40% body and chassis
weight reduction in FY2009.

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. Complete vehicle
system-level cost estimation is essential since it captures the cost
reduction potential due to both part integration and mass de-compounding
effect. 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 40%
body and chassis weight-reduction goal for FY2009.The cost-effectiveness
of the proposed weight-reduction goal is determined based on the vehicle
retail and life cycle cost analysis of a potential lightweight material
substitution scenario in various body and chassis 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 the proposed scenario
is then presented, followed by conclusions.

2.  Approach

2.1  Scenario Development 

Cost-effectiveness of a 40% body and chassis weight-reduction goal was
demonstrated based on a scenario analysis by 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
weight reduction goal was determined. Due to a significantly higher
weight reduction goal, carbon fiber-reinforced polymer-matrix composites
(carbon-FRPMCs) and aluminum were primarily considered for body and
chassis applications. These two materials have the potential to achieve
the desired weight-reduction goal. Only carbon-FRPMCs offer the
potential for greater than 50% reduction in the weight of body and
chassis components while providing strength five times greater than
steel for structural parts. Most applications of this material have been
in high-end vehicles and race cars. 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. 

Table 1 shows the 40% body and chassis weight-reduction scenario for a
mid-size passenger car considered in the cost-effectiveness analysis.
The scenario focuses on a plausible specific lightweight material option
(i.e., mainly carbon-FRPMC or aluminum) at the broad component category
level based on its near-term market potential to achieve the desired
overall body and chassis weight reduction goal. This scenario approach
allows determination of cost-effectiveness at a vehicle level, the
context important for the actual implementation and commercialization of
the lightweighting materials technologies in the market place. Specific
components considered under body and chassis vehicle subsystems 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 40% Body& Chassis Weight Reduction Scenario

SYSTEM

	Baseline	40% Weight Reduction Scenario

	Technology	Mass (kg)	Technology	Mass (kg)

Powertrain

Engine	V-6 3.0L DOHC AL/AL	197	V-6 3.0L DOHC AL/AL	192

Energy Storage	Lead-Acid, Standard	19	Lead-Acid, Standard	18

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

Transmission	Automatic (L5)	81	Automatic (L5)	79

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

Driveshaft/Axle	Generic	77	Generic	74

Differential	Generic	25	Generic	25

Exhaust System	Generic	48	Generic	48

Oil and Grease	Generic	15	Generic	15

Powertrain Electronics	Generic	10	Generic	10

Emission Control Electronics	Generic	10	Generic	10

Body

Body-in-White	Midsize steel unibody	320	Carbon Fiber Polymer Composites
(55% wt redn.)	144

Panels	Stamped Steel	60	Carbon Fiber Polymer Composites (55% wt redn.)
27

Front/Rear Bumpers	Sheet Steel	10	TP/Carbon Fiber (60% wt reduction)	4

Glass	Conventional, 4 mm	40	Polycarbonate (25% reduction)	30

Paint	Solventborne, avg color	12	Solventborne, avg color	12

Exterior Trim	Generic	10	ULSAB (35% wt. reduction)	7

Body Hardware	Generic	10	Generic	10

Body Sealers and Deadners	Generic	2	Generic	2

Chassis

Cradle	Generic	35	Aluminum (45% wt. reduction)	19

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

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

Wheels and Tires	Aluminum 15”	71	Magnesium 15" (40% wt. reduction)	59

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

Interior

Instrument Panel	Generic	26	Generic	26

Trim and Insulation	Generic	24	Generic	24

Door Modules	Generic	28	Generic	28

Seating and Restraints	Generic	66	Generic	66

HVAC	Generic	22	Generic	22

Electrical

33

33

Final Assembly

40

40

Total Body & Chassis Weight

(% less than baseline)

692

415

(40%)

Total Vehicle Weight

1525

1237

2.1.1 Carbon-FRPMC

Application of carbon-FRPMC in automobiles is quite limited and occurs
only in low-volume niche vehicles today such as Formula 1 race cars,
Mercedes-Benz McLaren SLR supercar, Mazda’s RX-8, Honda’s Legend
sedan, Mitsubishi’s Pajero SUV, and Nissan’s latest GT-R super
sports car. General Motors is using the Corvette ZR1 to study the
feasibility of high-volume carbon-FRPMC parts, whereas Toyota is
planning to use a body frame made of this material in its 1/X concept
car that will offer the same interior space as the Prius hybrid but only
weigh one-third as much. Most carbon-FRPMC applications include drive
shafts, spoilers, A-pillars, underbody structures, and various body
panels for high-performance, low-volume cars. Three Japanese companies,
i.e., Toray Industries, Teijin, and Mitsubishi Rayon, which control 70%
of the global carbon fiber market, are aiming to pioneer mass production
of this material for widespread use in cars. For example, Teijin who is
planning to start supplying carbon-resin composites to automotive parts
makers as early as 2010 via its subsidiary Toho Tenax, is aiming to
first make engine undercovers for high-range sports cars and then move
towards mass market models. Toray Industries has invested in a German
developer of carbon-FRPMC parts for cars and trucks, and is planning to
expand its sales for automotive applications to approximately $510
million by 2015, including ultimately mass-produce carbon-fiber parts
mainly for Toyota. Honda and Nissan have similarly joined with Toray and
Mitsubishi Rayon to research new, less-expensive carbon fiber for cars.

To achieve a significantly higher body and chassis weight reduction
goal, this analysis considers carbon-FRPMC for three major body
components as shown in Table 1. These three body components,
body-in-White (BIW), panels, and front/rear, have been considered as the
most suitable components application of this lightweight material since
these components contribute more than 25% of total vehicle weight.
Potential percentage weight reduction assumed for these components has
been in the mid range of 55-60%, although expected weight reduction has
been reported to be 45-80% compared to mild steel depending on specific
automotive part application. For example, Focal Project 3 of the
Automotive Composites Consortium (ACC)—a collaborative,
pre-competitive R&D partnership of the three big OEMs and
DOE—predicted a 66% BIW weight reduction with a total number of parts
less than 20 by demonstrating the potential on a carbon fiber B-pillar
(Iobst et al. 2007). Similarly, niche vehicles such as X-Power sports
vehicles have demonstrated 70% weight reduction potential in body panels
compared with steel (Marsh 2006). On the other hand, the structural
composite underbody targeted to be a part of the United States
Automotive Material Partnership (USAMP) Multi-Material Vehicle (MMV)
project has obtained only 29% weight reduction using carbon fabric for
floors. The project’s objective, however, was to capitalize on the
material’s strength to optimize the crash performance rather than to
reduce weight (Berger and Jaranson 2009). In fact, carbon-FRPMC is
currently not under further consideration in the MMV project and a new
project on carbon-FRPMC body structure to optimize the weight savings
potential has been under consideration for near-term funding. Use of
carbon fibers in Formula 1 cars such as Mercedes McLaren SLR in
monocoque design is 50% lighter than steel components (Marsh 2006), and
a 48% reduction in BIW mass without doors has been considered for a
composite monocoque using various combinations of carbon and glass
fibers in one of the earlier studies (Mascarin et al. 1995). 

2.1.2  Aluminum 

To achieve the desired 40% body and chassis weight reduction goal,
aluminum substitution was considered in several vehicle chassis
components, as shown in Table 1, including corner suspension, cradle,
braking system, and steering system. Aluminum (forged or cast) is
desirable in vehicle chassis components because it reduces un-sprung
weight of the suspension, thereby improving overall handling performance
and ride comfort. The cradle is the component assumed to have the most
weight reduction—45%—among the components considered here for
aluminum substitution. 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, with a weight reduction potential of 20-30%
compared to steel, have a 20% market share today. 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 achieved
in the single part. The weight reduction potential in each system is
assumed to be 5.5%. Although the wheels segment has seen consistent
growth in aluminum use, it is anticipated that the more aggressive
weight reduction goal will produce a shift from cast aluminum wheels to
cast magnesium wheels, the latter offering a 40% weight reduction
potential compared to cast aluminum wheels (EEA 2007). Like other
lightweight materials, high production-volume cost has been the limiting
factor that historically limited automotive growth. To date, an average
vehicle contains 10-12 lbs of magnesium, mostly as castings in the
instrument panel beam, transfer case, steering components, and radiator
support. There is a great need for development of wrought magnesium
products and manufacturing processes to provide improved mechanical and
physical properties, crash performance, and corrosion resistance before
magnesium’s use in more critical body and chassis applications can be
expanded. To achieve the total savings goal of 40% of the primary body
and chassis weight, a 35% reduction in exterior trim weight has been
assumed. This weight savings are consistent with the target weight for
the PNGV-Class vehicle which has a target weight of around 1000 kg
vehicle curb mass (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 40% 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. The cost-effectiveness
of lightweighting options depends considerably on the secondary savings
since those savings helps to reduce the overall effect of higher
lightweight material cost. 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
savings related to the two scenarios considered here are presented in
Table 2 along with other estimated major parameters in the
cost-effectiveness analysis. Total secondary weight savings are
estimated to be 49% of primary savings and depend on the number of
vehicle components considered. Most of the secondary weight savings
occur in the powertrain system and depend on the extent of powertrain
downsizing assumed. Since the ASCM includes secondary weight savings
only of major vehicle components (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).

Table 2.  Major Parameters Considered in the Cost-Effectiveness Analysis
of the 40% Body and Chassis Weight Reduction Goal

Parameter	

Baseline	40% Body and Chassis

Weight Reduction Scenario

Primary Body & Chassis Weight Savings	NA	277 kg (40%)

Secondary Weight Savings

Body & Chassis	NA	37 kg (5.3%)

Powertrain	NA	98 kg

Total	NA	135 kg

Body & Chassis Weight	692 kg	378 kg (45%)

Powertrain Weight	594 kg	485 kg (18%)

Engine Power	122 kW	93 kW

Final Vehicle Weight	1524 kg	1102 kg (28%)

Combined Fuel Economy 	23 mpg	27.2 mpg

Vehicle Lifetime Operation	120,000

Note: % values within parenthesis indicate savings with respect to
baseline steel

With the consideration of secondary weight savings, total body and
chassis weight savings are estimated to be 45.3% as shown in Table 2.
There will be a decrease in powertrain weight with powertrain resizing,
where engine power is estimated to decrease by 24%. The resulting
vehicle weight reduction has been estimated to 28%. 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 27.2 mpg with the
40% body and chassis weight-reduction goal. 

2.2 Cost Estimation Methodology

As with the earlier study (Das 2008), this analysis employs the
Automotive System Cost Model (ASCM), developed jointly by Oak Ridge
National Laboratory and Ibis Associates, Inc. in collaboration with
Argonne National Laboratory, to estimate the cost-effectiveness of the
40% body and chassis weight-reduction goal. 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 (some components have been shown in
aggregate form in Table 1 before) 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 and 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 Laboratory’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 advanced technologies being considered for vehicles today.
This cost model has been 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, insurance, local
fees, fuel, battery replacement, maintenance, repair, and disposal.
Financing, insurance, and local fees costs are dictated by the vehicle
retail price, while the fuel cost is dictated by the vehicle’s fuel
economy (estimates are shown in Table 2) and a gasoline price of
$1.90/gallon, based on near-term price trends (EIA 2009). 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 total vehicle lifetime
miles are 120,000—based based on average 10,000 miles driven annually
and a vehicle life of 12 years—and a discount rate of 10%.

2.3 Component Cost Data

Component technology cost data used in the analysis are mainly based on
the latest estimates developed by Ibis Associates, Inc. using results of
the recent studies developed for the industry (Ibis 2008 and Ibis
2009a). One such recent study stems from the USCAR-ACC composite
structure programs that have been involved in the detailed cost analysis
of carbon-FRPMC body structures. Even detailed cost analyses can have
limitations—in this case the limitation is that the program never
developed a complete design or high production-volume-scale cost
analysis for a fully functional BIW structure. 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 cost-effectiveness of the
plausible lightweight scenario to achieve the desired weight reduction
goal 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, based on
the detailed cost analyses available in the literature.

Several recent USCAR-ACC composite structure programs have been used in
order to extrapolate to a full BIW structure and panel system
functionally equivalent to the carbon fiber scenario considered
previously in ASCM. The ACC programs contributing to this analysis
include the FP2-composite truck box, FP3-carbon fiber structures, the
Composite Underbody program, and a recent fiber, preforming, and molding
technology tradeoff study (Ibis 2007, 2009b; Berger and Jaranson 2009
and Boeman and Johnson (2002)). The truck box study evaluated a high
volume composite design and process study employing P4 preforming and
SRIM molding. Similarly, the carbon fiber structures program
demonstrated a 60% mass savings over steel for a molded carbon fiber
composite, although this was a large pillar type component and not a
full vehicle structure.  The Underbody program examined a broad range of
concepts, including random and fabric glass, carbon, and high modulus
polypropylene (HMPP) reinforcement through sheet molding compound (SMC)
compression, long-fiber injection (LFI), and direct long-fiber
thermoplastic (DLFT) molding processes. The most recent ACC tradeoff
study compared glass, carbon, and natural fiber composites produced
through SMC, structural reaction injection molding (SRIM), and resin
transfer molding (RTM), and evaluated design based on equivalent
strength and stiffness. Mass savings on individual components relative
to steel ranged from 37% to 70% depending on the tensile or modulus
equivalency. As noted earlier, a mass savings of 55% has been assumed in
our case of carbon-FRPMC body structure, i.e., BIW and panels. The
production economics are based here on the recent studies using high
production rate P4 preforming and SRIM molding, achieving production
rates of 15 parts per hour. The carbon material pricing is based on
current volume pricing estimates of $30.80/kg ($14/lb), rather than the
optimistic $22/kg ($10/lb) used in some of the earlier studies, and
$4.24/kg for polyurethane systems.

The entire body structure and carbon SMC panel systems were modeled
using IBIS Technical Cost Models and the new regression analyses have
been conducted to establish updated cost relationships sensitive to
production volume, mass, material price, piece count, and part area.
Figure 1 shows the estimated cost sensitivity to annual production
volume of carbon-FRPMC body-in-white structures for a mid-size vehicle.
Estimated costs are based on the baseline BIW and panel mass of 128 kg
and 42 kg, respectively, representing a 49% reduction in mass compared
to the baseline steel body structures. As one would expect, carbon-FRPMC
body structure is quite insensitive to annual production volume since it
is a low-volume process: total part cost varies less than $20/part and
is relatively constant at around $2,960/part beyond production volume of
50,000 parts/year.

The cost sensitivity to annual production volume for body-in-white
structures of various materials is shown in Figure 2. The costs
represented in Figure 2 include 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. Current material pricing
is as follows: steel $0.77/kg; aluminum sheet $3.31/kg; aluminum casting
$2.86/kg; vinyl ester compound $4.24/kg; glass fiber $1.50/kg; and
carbon fiber $30.80/kg (reflecting a recent surge in demand for large
commercial jet aircrafts). Based on these material prices and masses
assumed, the carbon-FRPMC structure is more expensive than all other
lightweight material options considered here, except at annual
production volume of 10,000 parts, when the aluminum unibody is more
expensive than carbon-FRPMC. The crossover between these two materials
is estimated to occur between production volumes of 10K-25K. Unlike the
current estimate, most past studies indicate cost parity of carbon-FRPMC
with conventional baseline steel structure at a production volume in the
range of 5,000-35,000 (Kang 1998 and Fuchs 2008). Their estimates of
cost parity are mainly due to their assumption of lower carbon fiber
prices of $11-$17.50/kg, compared to this analysis’ assumption of
$30.80/kg. Fuchs (2008) estimated cross-over point of 35,000 for the
cost-effectiveness of traditional steel and carbon composites represents
45% of car models and 10% of all cars produced in North America in 2005.
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 curves for
composite body structures (i.e., for both glass-FRPMC and carbon-FRPMC)
are relatively flat compared to other materials. For our analysis, the
threshold production volume of cost-effectiveness is 240K parts/year for
baseline steel and 50K parts/year for the lightweight vehicle.

Figure 1. Carbon-FRPMC Body Structure Cost Sensitivity to

Annual Production Volume

Figure 2. Lightweight Material Body-In-White Cost Sensitivity to

Annual Production Volume

Figure 3. Aluminum Chassis Component Cost Sensitivity to Material Price

Figure 3 shows the per-part cost sensitivity to aluminum casting price
for four different aluminum chassis components considered under the
carbon-FRPMC scenario based on part weight used in a mid-size vehicle.
Note that the part cost estimates for the base price of $2.86/kg for
aluminum casting is also shown. The cost estimates for the aluminum
cradle includes not only casting cost, but also melting, scrap recovery,
machining, and corrosion protection. 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 for
replaced aluminum components are based on recent available estimates
(EEA 2007). Cost relationships consist of two components, i.e., material
and processing. As Figure 3 shows, the higher weight of the corner
suspension causes its cost to be higher and more sensitive than the
cradle is to aluminum ingot prices. The sensitivity of steering and
braking system costs to aluminum ingot pricing is not significant since
the aluminum components contributes less than 10% of total system weight
in each case. Cost of cast magnesium wheels are based on 15” wheels
and reflects current material pricing and processing technology
improvements and also includes tire costs. It has been assumed to have
20% price premium compared to cast aluminum wheels (EEA 2007 and Long et
al. 2005).

3.0 Results

Figure 4 shows the estimated cost savings resulting from the 40% body
and chassis weight savings of the carbon-FRPMC scenario compared to the
baseline, by major vehicle systems, vehicle retail price, and life cycle
cost. Only three major vehicle systems 

Figure 4. Estimated Cost Savings of 40% Body and Chassis

Weight Reduction Scenario

are considered because the cost of other vehicle systems—interior,
electrical, and final assembly—are assumed to be the same under all
scenarios. There would be $1490/vehicle increase in retail price level
and a $1100/vehicle increase in life cycle cost. The increase in vehicle
retail price is mainly due to the body system cost increase of about
$2200, the result of the higher cost of carbon unibody structure. The
cost savings due to the downsizing of the powertrain and chassis is not
sufficient to lower the vehicle retail price. In addition, with the
consideration of quite a few operation cost categories (e.g., financing,
insurance, and local fees) as functions of vehicle retail price and the
assumption of lower gasoline price of $1.90/gallon – a 40% weight
reduction goal cannot be achieved even at the level of life cycle cost.
It is estimated that if the price of aluminum used in chassis components
is reduced from the baseline price of $2.86/kg to $2.20/kg and carbon
fiber price is reduced from the baseline price of $30.40/kg to DOE’s
long-term target value of $6.60/kg, the cost-effectiveness at the life
cycle cost level could be achieved, even at the assumed gasoline price
of $1.90/gallon. As one would expect, the cost-effectiveness of
carbon-FRPMC vehicle would improve with higher fuel price as also shown
here in Figure 5. It is estimated that if the fuel price increased from
a baseline price of $1.90/gallon to about $4.25/gallon,
cost-effectiveness could be achieved at the level of vehicle life cycle
cost without requiring any material price reductions. It is anticipated
that a combination of material price decreases and a fuel price increase
would be necessary to achieve the cost-effectiveness of carbon-FRPMC
vehicle at the level of vehicle retail price.



Figure 5. Vehicle Life Cycle Cost Sensitivity to Fuel Price

4.0 Conclusions

Cost-effectiveness of ALM’s 2009 body and chassis weight reduction
goal of 40% in light-duty vehicles was assessed based on the use of
lightweight material options for various body and chassis components
under a plausible mid-size vehicle scenario. The weight reduction goal
here is very similar to that of the Japanese government whose intention
is to mass-produce a cost-effective, recyclable carbon fiber and use it
to achieve a 40% reduction in cars by the middle of the next decade
(Brooke 2009). The lightweight material substitution options considered
here focused on carbon-FRPMC for body systems and aluminum for chassis
components. Among potential lightweighting materials, carbon-FRPMC has
the greatest weight savings potential. The analysis also considers the
effect of primary weight savings of 40% on other vehicle components that
can be resized while maintaining the same level of vehicle performance
with the reduced vehicle weight. This weight savings are known as
secondary weight savings. Due to consideration of secondary weight
savings, total body and chassis weight savings are estimated to be 45%,
whereas the final vehicle weight savings of 28%. Cost-effectiveness of
40% 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 recent major studies, thereby
reflecting the latest technology developments and material prices.

Even with the consideration of powertrain resizing and secondary body
and chassis mass savings, carbon-FRPMC lightweight material vehicle
option is not cost-effective in meeting the ALM 40% body and chassis
weight savings goal from the life cycle cost perspective if the recent
low gasoline price trend continues. The higher cost results mainly from
using the carbon-FRPMC body system which is $2200 more expensive than
the baseline system. The higher cost is not offset during the vehicle
operation stage. The higher vehicle retail price also affects some of
the operation cost categories such as financing, insurance, and local
fees which are functions of vehicle retail price. The vehicle retail
price is estimated to be $1492 higher than baseline. The life cycle cost
is $1102 higher. From the life cycle cost perspective, either a change
in material price or fuel price would be necessary to achieve the
cost-effectiveness goal. Aluminum and carbon fiber prices need to be at
$2.20/kg and $6.60/kg, respectively, whereas fuel price needs to be
$4.25/gallon for the lightweight vehicle to be cost effective. It is
likely that a combination of material and fuel prices would be necessary
to achieve the cost-effectiveness at the level of vehicle retail price,
which is the primary consideration of OEMs for determining the viability
of any new vehicle technology. The extent of the necessary price changes
would depend on the extent of secondary mass savings considered, with
this analysis employing a conservative estimate of secondary mass
savings. In contrast to this conservative estimate, General Motors 1992
Ultralite carbon body structure weigh 191 kg (compared to the 171 kg
body structure in this analysis) demonstrated a super-lean 635 kg curb
weight concept car—considerably lower than our estimated curb weight
of 1102 kg. 

Findings in this analysis are consistent with the earlier findings that
carbon-FRPMC is too expensive for large scale application in light-duty
vehicles today. Composite monocoque BIW designs considered in the past
several studies indicate cost to be in the range of 41-73% higher than
the steel unibody, depending on the type of tooling used (Mascarin et
al. 1995). The technology is suited for mainly low annual production
volume, and a reduction in carbon fiber price would help to a large
extent in improving its viability. Vehicle platforming considerations
which allow low annual production volumes would facilitate the
competitiveness of carbon-FRPMC body structure (Fuchs et al. 2008).
Lightweighting also improves the cost-effectiveness of advanced
technology vehicles by lowering the expensive powertrain cost while
maintaining the performance (Aluminum Association 2008, Brooke 2009, 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. With a higher lightweighting goal, reduced material cost become
more critical because it is such a large share of the total part costs
particularly in low production volume production manufacturing
processes. Accordingly, a current focus of DOE’s lightweight materials
program is the development low cost carbon fibers from alternative cheap
renewable resources and high-volume processing of composites.

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.

Berger, L. and Jaranson, J. (2009). “Automotive Composites Consortium
Focal Project 4,” FY 2007 Progress Report for Lightweighting
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Washington, DC, Available at:
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Boeman, R. G. Johnson, N. L (2002). “Development of a Cost
Competitive, Composite

Intensive, Body- In-White,” SAE Paper No. 2002-01-1905, the Society of
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Brooke, L. (2009). “A Featherweight Future,” Automotive Engineering
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Das, S. (2005). “Lightweight Opportunities for Fuel Cell Vehicles,”
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Das, S. (2008). “Cost-Effectiveness of a 25% Body and Chassis
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Energy and Environmental Analysis, Inc. (EEA) (2007). “Analysis of
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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

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,
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

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

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