## DRAFT

**COST -**  **EFFECTIVENESS OF A 25% BODY AND CHASSIS**  **WEIGHT -**  **REDUCTION GOAL IN LIGHT -**  **DUTY VEHICLES**
Sujit Das
En ergy and Transportation Science Division Oak Ridge National Laboratory Prepared for Li ghtweighting Materials Office of Vehicle Techn ologies U. S. Department of Energy



### August **200 8** 

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
- 00OR227252 **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 econom y o f at least 35 mpg b y 2020 , the pressure to lightweight vehicles is stronger than ever before. Vehicle lightweighti ng represents one of several design approaches automakers are currentl y evaluating to i mprove fuel economy
. Li ghtweight i ng is ty

pically accomplished by

downsizing , integrating parts and functions, substituting materials, or by combin ing these methods. Li ghtweighting Materials ’ (LM ’s ) component of the U.S. Department of Energy ’s Vehicle Technol o gi es program focuses on the development and validation of advanced materials and manufacturing technologies to significantl y 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 an d manufacturing technologies by 2010 that, if implemented in high volume, could cost
- effectivel y reduce the weight of passenger - vehicle body and chassis sy stems by 50% with safety, performance, and recyclability

comparable to 2002 vehicles. In order to ach ieve this long
- term weight
reduction goal , LM has set annual intermediate weight
- reduction goal s, starting with 10% in FY2007, and finally

achieving 5 0 % by

FY2010. This paper focuses on the 25% body and chassis weight
- reduction goal of FY2008, with emphasi s on the assessment of cost
effectiveness to achieve this desired goal. To achieve its long
- term weight
- reduction goal , LM has prioritized its research areas in several lightweight ing materials including advanced high
- strength steel, aluminum, magnesium, titanium, and composites . Composites includ e metal
- matrix materials and glass
- and carbon
- fiber reinforced thermosets and thermoplastics. Over the past several ye ars, the LM R&D portfolio has included a ssessment s of various lightweight body and front
- end s tructures , such as those constructed of advanced high
- strength steel, composite
- intensive, and magnesium . These assessments, either co mpleted or underway , include, for example, one in which the goal is to design, anal yz e, and develop the technology

for a c omposite
- intensive, body
- in
- white structure that achieve s a minimum of 60% weight savings over steel. Additionall y, the latest LM multi
- material vehicle (MMV) project aims to sy nthesize and demonstrate these various lightweight material component options i n a single vehicle. Cost remains one of the major obstacles to successful market penetration of thes e 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 c ost - effectiveness of the proposed weight
reduction goal is determined based on the vehicle retail and life cycle cost anal ys es of scenarios of potential lightweight material substitution in various body and chassis3

components to achieve the desired weight
- reduction goal . Cost methodology and potential data sources for the anal ys is are then discussed. Cost data collected for various vehicle components cons idered for achieving the weight reduction goal are then discussed , as are the assumptions and methodology used. A discussion of the r esults of the cost anal ys is of proposed scenarios is then presented, followed b y conclusions
. **2. Approach**  **2.1 Scenario**  **Development** Cost
- effec tiveness of a 25% body and chassis weight
- reduction goal w as demonstrated based on scenario analy si s with each scenario focusing on a specific lightweight material ty pe substitution at a major vehicle
- component level
. A representati ve mid
- size vehicle , i.e. Honda Accord , was considered as the baseline against which the cost - effectiveness of scenarios w as determined
. Two plausible material scenario

—one for aluminum and another for glass fiber
- reinforced pol ym er - matrix composites (glas s - FRPMCs)

— have be en de velop ed 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 c astings 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 w eight reduction potential range of 30
- 50% compared to conventional steel
. Glass
FRPMCs are used less than aluminum in today ’s vehicle , and their application is limited to complex non
- structural assemblies . G lass
- 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 anal ys is
. Each scenario focuses on a specific lightweight material option
. T his 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. Parts considered for the lightweight material substitution are based on the ir near - t erm market potential; the specific total number of parts considered under each scenario i s dictated by the material type and i ts weight reduction potential for achiev ing the overall body and chassis weight reduction goal. Specific components considered under body and chas sis vehicle subs ys tems for both scenarios are highlighted in Table 1 (in bold ty pe) . 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 re duction assumed in each case is based on the best estimated value available in the literature today
. T he definition s of various vehicle components are based on the Automotive Sy stem Cost Model (ASCM , discussed below) and are provided in Appendix A.**Tab le 1.**  **Mid -**  **Size 25% Body& Chassis Weight Reduction Scenarios 1** 

**SYSTEM Baseline**  **Glass -**  **FRPMC (25% Weight Reduction) Scenario**  **Al uminum**  **(25% Weight Reduction) Scenario Technology**  **Ma ss** 

**(kg) Technology**  **Ma ss**  **(kg) Technology**  **Ma ss**  **(kg) Powertrain**  Engine V - 6 3.0L DOHC AL/AL 19 7 V - 6 3.0L DOHC AL/AL 19 7 V - 6 3.0L DOHC AL/AL 19 7

Energy Storage Lead -Acid, Standard 1 9 Lead -Acid, Standard 1 9 Lead -Acid, Standard 1 9 Fuel System Gasoline, 17 gal 83 Gasoline, 17 gal 83 Gasoline, 17 gal 83 Transmission Aut om atic (L5) 81 Automatic (L5) 81 Automatic (L5) 81 P/T Thermal Generic (car) 29 Generic (car) 29 Generic (car) 29 Driveshaft/Axle Generic 7 7 Generic 7 7 Generic 7 7 Differential Generic 25 Generic 25 Generic 25 Exhaust System Generic 48 Generic 48 Generi c 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 -Wh ite Midsize steel unibody 3 20 **Glass Fiber TS/Composite ( 30**  **% wt redn.)**  **2 3**  **2 Al**  **uminum Unibody (40% wt redn.)**  **17 6**  Panels Stamped Steel 60 **Glass Fiber TS/Composite ( 2**  **5% wt redn.) 39**  **Stamped A luminum (40% wt**  **r edn.)**  **36** Front/Rear Bumpers Sheet Steel 10 **Stamped A luminum**  **( 40**  **% wt redn.) 6**  **Stamped A luminum**  **( 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 **ULSA B (35% wt reduction)**  **6.5** Generic 10 Body Hardware Generic 10 Ge neric 10 Generic 10 Body Seal ers and Deadners Generic 2 Generic 2 Generic 2 **Chassis** Cradle Generic 35 **Cast Al**  **uminum ( 4**  **5% wt redn.) 19**  Generic 35 1 All weights in the table denote values after primary weight savings only
.5

**SYSTEM Baseline**  **Glass -**  **FRPMC (25% Weight Reduction) Scenario**  **Al uminum**  **(25% Weight Reduction) Scenario Technology**  **Ma ss** 

**(kg) Technology**  **Ma ss**  **(kg) Technology**  **Ma ss**  **(kg)** Corner Suspension Generic 4 7 **Al uminum**  **(3 5**  **% wt. reduction) 31**  Generic 4 7 Braking System ABS 4 8 **Al umin**  **um (5 .5**  **% wt. reduction) 45**  ABS 4 8 Wh eels and Tires Aluminum 15” 71 **Al uminum 15"**  **– Forged (11% wt. redn.)**  **6 3**  Aluminum 15” 71 Steering System Generic 2 7 **Al uminum**  **(5.5 % wt. reduction)**  **26** Generic 2 7 **Interior** Instrument Panel Generic 26 Generic 26 Gen eric 26 Trim and Insulation Generic 24 Generic 24 Generic 24 Door Modules Generic 28 Generic 28 Generic 28 Seating and Restraints Generic 66 Generic 6 6 Generic 6 6

HVAC Generic 22 Generic 22 Generic 22 **Electrical** 33 33 33 **Final A ssembly**  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 Scen arios** **2.1.1 Aluminum**

A luminum 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 str ucture achievi ng 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. Un der s imple 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 a ctual 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 non
optimized steel design. Recent study b y 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 alum inum intensive concept vehicles, the Ford Taurus 1997 , an effort i nitiated in late 1990s (Aluminum Association 2008)
. A lower weight reduction potential of 45% has been used in our anal ys is in order to achieve the overall body and chassis weight reduction goal. A 40% weight reduction assumption for closure panels is cons istent 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 goo d example of a successful aluminum bolt
- on high volume application
. **2.1.2 Glass -**  **FRPMC** Application of gl ass - FRPMC in automobiles is quite limited and occurs only in low
volume niche vehicles today such as Chevy Corvette, Dod ge Viper, and Cadillac XLR. The highest volume of composites use in Class A exterior applications is in the fascia sy stems. Similarly , exterior non
- class A composites use is currentl y limited to a select few applications such as pickup truck box inner pane ls, 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. C on sideration of glass
- FRPMC in our anal ys is 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 , co mpared to 25% value reported for reinforced reaction injection molded poly urea/glass flake body structure (Dieffenbach and Mascarin 1993)
. However, for glass
- FRPMC panels, a 2 5% weight reduction was assumed consistent with the available estimates
. Recent results of the United States Automotive Materials Par tnership (USAMP) Multi
- Material Vehicle (MMV) project on the composite underbody has considered several glass
- fiber reinforced pol ym er options providing a weight savings potential of 7
- 40% compared to the steel baseline, the upper limit of reduction availa ble 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 in7

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 reduct ion goal
. Aluminum has been considered for front/rear bumpers, corner suspension, cradle , braking s ys tem, steering s ys tem, and wheels and tires
. Aluminum (forged or cast) is desirable in vehicle chassis components since it reduces un
- sprung weight of the s uspension, 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., 4 5 % vs. 40%. Aluminum penetration has been relativel y high in steering knuckles , an d 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 potenti al of 30.5% and 43%, respectively (EEA 2007)
. However, in both cases, the substitution of a single component in the s ys tem achieves a relativel y 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 futur e. 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 3 5% reduction in exte rior 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 (U LSAB
- AVC 1999). **2.1.3 Secondary Weight Savings**  The objective for the selec tion 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 s econdary 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 allow s comparisons of functionally equivalent vehicle designs

—a reduced vehicle weight require s a less powerful engine to achieve equivalent performance (i.e., acceleration, range etc.). Secondary weight savings have been estimated b y ASCM and those related to the two scenarios considered here are presented i n Table 2 , along with other es timated major parameters in the cost -8

effectiveness anal ys is. 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 considere d for primary weight savings. Total secondary weight savings is estimated to be 70% and 4 4 % of primary savings for aluminum and glass
- FRPMC lightweight material scenarios, respectivel y. 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. M ost estimated secondary weight savings o ccur in the powertrain sy stem under both scenarios. Absolute secondary w eight 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 se condary 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 e stimated to be 31.6% and 2 6
. 1 % for aluminum and glass
- FRPMC scenarios, respectivel y, higher than the 25% primary weight reduction goal as shown in Table 2. There will be a decrease in powertrain weight with p o wertrain resizing, where engine power is estimated to decrease b y 14%. The resulting percentage vehicle weight reduction for the corresponding scenarios has been estimated to 19% and 1 6 %, **Table 2. Estimated Major Parameters Considered for Cost**  **- effectiveness of 25%** 

**Body and Chass is Weight Reduction Goal**  **Parameter Baseline**  **25% Body and Chassis Weight Reduction Scenario**  **Aluminum Glass**  **- FRPMC**  Primary Body & Chassis Weight Savings NA 17 2 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 miles9

respectivel y. 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 econom y, after a vehicle has been full y redesigned to account for the reduced power demands of a lower mass. Combined vehicle fuel econom y would increase from the baseline value of 23 mpg to 25.9 mpg and 25.5 mpg for aluminum and glass
- FRPMC scenarios, respectivel y, 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 ye ars, respectivel y. **2.2 Cost Estimation Methodology**  The c ost - effectiveness of the 25% body and chassis weight
- reduction goal w as 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 subs ys tems (powertrain, chassis, body , interior, and electrical) consisting of more than thirty
- five components base d 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 & Ap pendix A). E ach component represent s a specific manufacturing technology . Vehicl e retail price based on the sum of manufacturing cost (i.e., costs of components and assembl y) , overhead, and selling is added to vehicle operation costs for the vehicle life cycle cost estimation. The interrelationships among vehicle subs ys tems and their effect on vehicle manufacturing cost are addressed, allowing inclu sion 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 fir st principles of phy sics, 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) hy

brid vehicle cost mode l (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 hy brid electric vehicle configurations and performance strategies (P lotkin 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 to day . This cost model has been recently integrated into the vehicle performance model PSAT (Powertrain Sy stem Anal ys is Toolkit) developed b y 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 co nsidered 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 cost s are dictated b y the vehicle retail price, and so is th e fu el cost b y fuel economy ( estimates are shown in Table 2 ) and an assumed gas oline price of $4/gallon in this anal ys is. With the exception of maintenance and repair, all other operation cost categories vary with the two lightweighting scenarios considered he re 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 1 2 ye ars , 120,000 vehicle lifetime operation miles, and a discount rate of 10%. **2.3 Component Cost Data** Co mponent technology cost data as highlighted b y bold letters under the two scenarios in Table 1 w ere collected mainly based on the latest estimates developed by Ibis Associates, In c. using results of the recent studies developed for the industry (Ibis 2008)
. For example, both the Aluminum Association and USAMP have recentl y been involved in the detailed cost analy sis of aluminum and glass
- FRPMC body structures, respectivel y. For other lightweight component technology costs considered here, where detailed ana lyses were unavailable, existing I bis cost models developed for the relevant mate rials sy stems 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 origina l model, since our objective in this analy sis is to determine the relative cost effectiveness 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 analy ses available in the literature. The c ost estimate of the aluminum unibody structure is based on the latest detailed evaluation by

the Aluminum As sociation, 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 anal ys is of multiple scenarios results, cost relationships of structure, panel, and assembly have been develop ed separatel y as a function of part mass, material price, part count, part area, and annual production volume which were then used in the anal ys is 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 typ e (glass vs. carbon) and form (random vs. fabric) and manufacturing technologies were considere d 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 f or compression of sheet molding compound was used for the anal ys is here. The sheet molding compound was modeled as a separate operation by11

molders, either as a profit center for companies with internal compounding or as a material purchased from a separate co mpany . 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 comp onents 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 informati on and molding processing technology
. Figure 1 shows the estimated cost sensitivity to annual production volume of three types of body
- in
- wh ite structures considered in this analy sis. The cost of bo dy- in
- white structure in cludes the assembly cost . Cost gr aphs 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 anal ys is here. For example, baseline mass es 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, v inyl e ster compound at $4.24/kg, and glass fiber at $1 .50/kg) and masses assumed, the aluminum unibody structure is alway s more expensive than steel, wh ereas TS/glass composites are competitive at annual production volume up t o 6 0 ,000 parts. M ost 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 t o 105 ,000, which represents 68% of car models and 29% of all cars produced i n North America in 2005 (Fuchs 2008). The cost sensitivities of steel and aluminum structure s 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 glass
0 500 1000 1500 2000 2500 3000 3500 4000 4500

0 25 50 75 100 125 150 175 200 225 250 275 300 **An nua**  **l Pr oduct**  **ion Volume ( K)** **B o** **d y** **- I** **n -** **W h** **i t** **e S** **t r** **u c** **t u** **r e** **C o** **s t** **( $** **/ p** **a r** **t )** 
Steel U nibody Al um inum

U nibody TS/ Glas s Co mp os it e

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

**Annual Production Volume**12

FRPMC body

structure is relativel y flat compared to other materials. For our anal ys is, 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 f our different aluminum chass is 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 anal ysis 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 s ys tems were made by adding the estimated cost of replaced aluminum component (e.g., brake actuators and steering wheel column for braking and steering s ys tems, respectivel y) to the unchanged original balance of s ys tem 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. A s 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 a luminum ing ot price
. The material price cost sensitivity of steering and braking s ys tem cost is not that high since aluminum component in each case c ontributes to less than 10% of total sy stem 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**  **($/kg) P** **a r** **t C** **o s** **t (** **$ )**  Brake System Wh eel s & Tires Steering Sy ste m Chas si s Corner Su spens ion

Base Price $2.86/k g
**Figure 2. Aluminum Chassis Component Cost Sensitivity to Mate rial Price** 13

**3.0 Results** Figure 3 shows the cost savings for the two scenarios compared to the baseline, by major vehicle s ys tems, vehicle retail price , and life cycle cost
. Only three major vehicle s ys tem cost savings have been considered in this figure as defined in ASCM and listed in Table 1 , since other s ys tem costs (i.e., interior, electrical, and final assembl y) have been assumed to be the same under all scenarios. Vehicle retail price would increase by about $ 180 /vehicle under the aluminum scenario, h owever 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

s ys tem cost increase of about $1000 , the result of the higher cost of aluminum body

structure. The c ost savin gs 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 baselin e price of $3.31/kg to $2.95/kg , the cost
- effectiveness at the vehicle retail price could then be achievable. The improved fuel econom y under the aluminum scenario lowers fuel cost s significantl y

— enough to offset small increases in the small i ncrease in vehicle retail price

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

**-1500 -1000**  **-500 0**  **500 1000**  **1500 2000** 

**Alu min**  **um Gla**  **ss-FR PM**  **C C** **o s** **t S** **a v** **i n** **g s** **( $** **/ v** **e h** **i c** **l e** **)** Pow e rt ra in Body Ch as si s Ve hic le R

etai l P ri ce Op er ation Li feC ycl e C os t

**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 s ys tem 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 expensiv e than thermoset glass
- FRPMC structure at all annual production volumes. Powertrain sy stem and chassis sy stem cost savings are lower in the glass
- FRPMC scenarios because the overall vehicle weight reduction is less than in the aluminum scenario, the differ ence being less secondary weight savings for glass
FRPMC. Higher aluminum price has also contributed to lower chassis s ys tem cost savings in this case. Cost savings in terms of vehicle retail price and life cycle cost are estimated to be about $280 and $16 00, 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 C onclusions**  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 sce narios, each scenario focusing on a specific lightweight material option, i.e., aluminum or glass
FRPMC. L ightweight material substitution options considered here focused on under body s ys tem s ; but additional chassis components for substitution were also s elected for the glass
- FRPMC scenario to achieve the desired overall weight reduction goal. The anal ys is also considers the e ffect of primary weight savings of 25% on other vehicle components that can be resized while maintaining th e same level of vehicle p erformance 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 ty pe of components for p rimary weight savings
. Due to consideration of secondary weight savings, total body and chassis weight savings is estimated to be in the range of 2 7
- 32%, whereas final vehicle weight savings of 1 6
- 19%. Cost
- effectiveness of 25% body and chassis weight redu ction goal is estimated in terms of both vehicle retail price and life cycle cost using the detailed 35+ component level automotive sy stem cost model developed by ORNL and Ib is Associates, In c. Cost data of components considered for lightweight material su bstitution are collected from the recently completed major studies, thereb y 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 cos t - 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 econom ic 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 p rice level
. Because of the consideration of secondary mass savings, the cost penalty due to lightweight i ng 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 saving s, it is likely that a significantly higher fuel price would be necessary if the cost
- effectiveness without secondary mass savings e ffect 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 anal ys is are consistent with the latest findings by the Aluminum Association although complete secondary mass savi ngs 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 considerat ion of powertrain resizing and other subsy stems ’ weight savings
. Furth ermore, 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 b ut 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 als o has been noted in the latest study (Fuchs (2008). L ightweighting 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 perspective s 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 Analy sis: Hy brid Drive and Diesel Fuel Vehicles,” Research Report No. 2008
- 05, written b y Ibis Associates, Inc. for the Aluminum Associ ation. American Iron and Steel Institute (AI SI ) (2001). “UltraL ight 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 Rid ge, TN, Feb. 19. Das, S. (2004). “A Comparative Assessment of Alternative Powertrians and Body
- in
White Materials for Advanced Technology Vehicles,” SAE Paper No. 2004
- 01
- 0573, the Society

of Automotive Engineers, Warrendale, PA. Das, S. (2005). “Lightwe ight 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 Sy stems: A Life
- Cycle Cost Comparison,” Journal of Metals, Vol. 45, No. 6, pp. 16
- 19, June. Energy and Environmental Anal ys is, Inc. (EEA) (2007). “Anal ys is of Light
- Duty Vehicle Weight Reduction Potential,” draft final report submitted to the U.S. Department of Energy , Office of Policy , Arlington, VA, July
. Fuch s, E. R. H. Field, F. R. Roth, R. and Kirchain, R. E. (2008). “Strategic Materials Selection in the Automobile Body: Economic Opportunities for Poly mer Composite Design,” Composites Science and Technology , Vol. 68, pp. 1989
- 2002. Ibis Associates, Inc. (Ib is) (2008). “Data Document: ORNLAutomotive Sy stem Cost Model,” Waltham, MA, July 1. Malen, D. E. and Reddy, K. (2007). “Preliminary Vehicle Mass Estimation Using Empirical Subsy stem 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 Lightweight i ng Vehicle Closure Panels,” SAE Paper No. 2008 01
- 0379, the Society

of Automoti ve Engineers, Warrendale, PA. Plotkin, S. et al. (2001). “Hy brid Vehicle Technology

Assessment: Methodology , Analy tical Issues, and Interim Results,” Argo nne 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 L ightweighitng Materials: FY 2007 Progress Report, Washington, DC. Ultra light Steel Autobody

– Advanced Vehic le Concepts (ULSAB
- AVC) (1999). “Description of UL SAB
- AVC Benchmarking and Target Setting,” Southfield , MI
. Nov. 18.18 

### Appendix A **ASCM Vehicle Co**  **mponent Definit i**  **on ASCM**  **UPG ASCM Description** 

**Group Name**  **Pow ertrain**  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, l ubrication, 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.

Ma ybe 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 c lutch, 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. Drive shaft/ Ax le 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) Ex haust System 36E

36O Ex haust System

Catalytic Converter All exhaust equipment after the manifold; pipe: catalytic

converter, muffler. P owertrain 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 p ower 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, transmissi on oil, miscellaneous lubricants19 **ASCM UPG**  **ASCM Description**

**Group Name**  **Bod y**  B IW 11A - 11B Body in W hite and closures The Body - In -Wh ite is the primary vehicle structure,

usually a single - body assembly, consisting of engine compartment, passenger cabin, and storage. Closure panels (including h inge 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 ass emblies, 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 engin e 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. Wh eels and Tires 36A 36C Wh eels, Ti res, 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. **Inter ior**  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 exter ior, 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 accesso ry 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 a nd 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 assemblie s 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 Wi ring and control s 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 14,2 0 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 veh icle subsystems under which components are grouped