Document ID: EPA-HQ-OAR-2010-0162-3493
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-08-29T04:00Z

DRAFT
                                       
                                       
                                       
                                       
                                       
                                       
COST-EFFECTIVENESS OF A 50% 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
                                       

                                   May 2010
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                         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 50% Body and Chassis Weight-Reduction Goal 
                            in Light-Duty Vehicles
                                       
                         Oak Ridge National Laboratory
                                   May 2010
                                       
1.  Background

With the recent higher gasoline prices and 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. Vehicle lightweighting represents one of several design approaches automakers are currently evaluating to improve fuel economy. The next few years will see considerable lightweighting across the automotive industry. Lightweighting is typically accomplished by downsizing, integrating parts and functions, substituting materials, or by combining these methods. Lightweight 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 earlier studies that focused on the 25% and 40% body and chassis weight-reduction goals of FY2008 and FY 2009, respectively (Das 2008, Das 2009). The present study emphasizes the assessment of cost-effectiveness to achieve the desired goal of 50% body and chassis weight reduction in FY2010.

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 than on vehicle life cycle cost.

This paper provides an assessment of the cost-effectiveness of a 50% body and chassis weight-reduction goal for FY2010 using the same methodology as used in the past two studies. 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 50% 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 the weight reduction goal was determined. Due to a significantly higher weight reduction goal, carbon fiber-reinforced polymer-matrix composites (carbon-FRPMCs) and magnesium 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. 

Current application of these lightweight materials is limited today. Carbon-FRPMCs have been used primarily in high-end vehicles and race cars. Magnesium use in today's light-duty vehicles is limited to less than 10 lbs/vehicle, mainly in interior applications such as instrument panels and parts of the steering structure. It can be found in various mainstream models (e.g., Cadillac models CTS, SRX, STS, Seville; Opel Vectra; BMW Mini, 5 and 7 Series; Rolls-Royce Phantom ; Daimler Chrysler's SL Roadster; the Jaguar X-type; or the Alpha Romeo 156). New automotive magnesium components gaining interest are front end structures, engine cradles, center consoles, and powertrain applications. The recent analysis by Meridian Lightweight Technologies indicates a 200 lbs total vehicle weight savings potential by magnesium use in mid-size vehicles. 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.

Table 1 shows the 50% 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 substitution option (i.e., mainly carbon-FRPMC and magnesium) at the broad component category level based on the materials' near-term market potential to achieve the desired overall body and chassis weight reduction goal. For a few vehicle systems, such as glass, paint, exterior trim, and body hardware, weight reduction has been based on either on a material other than carbon-FRPMC or magnesium, or as a factor of the vehicle's overall reduced weight. Figure 1 shows the material composition comparison of two alternative vehicle scenarios by six major material categories. To achieve the 50% weight reduction goal, the distribution of material types would change significantly. At the expense of conventional steel, magnesium and polymer/composites use would increase significantly by 10 and 1.7 times, respectively.

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. 

Figure 1.  Material Composition of the Baseline and Alternative Vehicle Scenarios

       Table 1. Mid-Size 50% Body& Chassis Weight Reduction Scenario
SYSTEM

                                   Baseline
                         50% 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
                                      197
                                                                 Energy Storage
Lead-Acid, Standard
                                                                             19
Lead-Acid, Standard
                                      19
                                                                    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
                                      77
                                                                   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 (68% wt redn.)
                                      102
                                                                         Panels
Stamped Steel
                                                                             60
Carbon Fiber Polymer Composites (68% wt redn.)
                                      19
                                                             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 (25% wt. reduction)
                                       9
                                                                  Exterior Trim
Generic
                                                                             10
ULSAB (50% wt. reduction)
                                       7
                                                                  Body Hardware
Generic
                                                                             10
Lightweight (50% wt. reduction)
                                       5
                                                      Body Sealers and Deadners
Generic
                                                                              2
Generic
                                       2
Chassis

 
                                       
                                                                         Cradle
Generic
                                                                             35
Magnesium (60% wt. reduction)
                                      14
                                                              Corner Suspension
Generic
                                                                             47
Magnesium (45% wt. reduction)
                                      26
                                                                 Braking System
ABS
                                                                             48
Magnesium (7% wt reduction)
                                      45
                                                               Wheels and Tires
Aluminum 15"
                                                                             71
Magnesium 15" -- (17% wt. reduction)
                                      59
                                                                Steering System
Generic
                                                                             27
Magnesium (7% wt. reduction)
                                      25
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
                                                                               
 
                                      346
                                     (50%)
Total Vehicle Weight

                                                                           1525

1180

2.1.1 Carbon-FRPMC

Application of carbon-FRPMC in automobiles is quite limited and occurs mostly 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. BMW has been using carbon fiber composites in its vehicles for a number of years in applications such as the roof of the M-series 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. Recently, the new Lexus LFA premium sports car has been designed with a carbon fiber cabin that weighs 200 kg less than a comparable aluminum cabin while maintaining the same rigidity. Most carbon-FRPMC applications today 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, that 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, which 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-end 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-producing 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. In 2009, the SGL Group formed a joint venture with BMW for the development of the material for use in BMW's Megacity vehicle, where carbon fiber composites will make up as much as 10-15% of the final vehicle weight. 

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 the specific automotive part application. For example, on the equivalent modulus basis and a minimum 75 vol.% resin requirement to facilitate the sufficient wetting out of carbon fibers, carbon-FRPMC has been shown to have a 64-70% weight reduction potential compared to glass fiber but with the manufacturability limitations for having less than 2.5 mm thickness (Ibis 2009c). Focal Project 3 of the Automotive Composites Consortium (ACC) -- a collaborative, pre-competitive R&D partnership of the three big U.S. 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 40% reduction in BIW mass without doors and the roof has been reported for the Lamborghini Murcielago using carbon/epoxy body material over its an all-aluminum body predecessor (Feraboli and Masini 2004). Our 68% weight reduction assumption using carbon-FRPMC for two body components (out of total three body oconsidered here for substitution) is more of an optimistic case dictated by the overall 50% body and chassis weight reduction goal.

2.1.2  Magnesium 

Most use of magnesium today has been as high pressure die casting (HPDC) components in a broad range of non Class A-surface vehicle applications such as cross-beam members and dashboard supports where a single cast component can replace various conventional multi-component steel fabrications cost-effectively. While the growth of magnesium die casting applications seems assured, there are other applications such as wheels, suspension arms, subframes, etc. where significant weight saving could be achieved but which require higher integrity than that provided by the HPDC process. For automotive chassis and body applications, magnesium offers a number of benefits. In terms of specific strength and stiffness, and buckling resistance, magnesium alloys compare favorably with both steel and aluminum. In the field of chassis applications, Porsche has quite a long experience with magnesium wheels and GM has been offering cast magnesium wheels for the Corvette since 1998. However, magnesium wheels have not been applied beyond these special sport car applications to the high-volume vehicle market due to their much higher costs and potential corrosion problems. The general experience, however, with material competition in North America has been that the magnesium design is displaced when a lower-cost solution for a particular weight trimming issue becomes available.

To achieve the 50% body and chassis weight reduction goal, magnesium substitution was considered in five vehicle chassis components, i.e., corner suspension, cradle, braking system, steering system, and wheels and tires, as shown in Table 1. Magnesium use in cradle and corner suspension would provide 60% and 45% weight reduction, respectively. The potential weight reduction in the corner suspension is less than in the cradle because magnesium's use in the suspension is limited to control arms and steering knuckles, parts that account for about 47% of the total corner suspension weight when aluminum is used. Magnesium use would provide a further 30% weight reduction in these two parts compared to aluminum. The magnesium cradle weight reduction potential has been based on the USAMP Corvette magnesium cradle design, which has been estimated to yield a 33% weight reduction compared to aluminum. Both steering and braking systems would experience a 7% weight reduction with magnesium use, since the application is limited to the steering wheel column in the steering system and the brake actuators in the braking system. Magnesium use in steering wheel columns -- which account for 15% of the overall system weight -- would provide an additional 25% weight reduction compared to aluminum. For wheels and tires, the total system weight reduction is estimated to be 17% based on the 40% weight reduction magnesium provides in the wheels. To achieve the total savings goal of 50% of the primary body and chassis weight, a 50% reduction in body hardware weight has been assumed. These 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 50% 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 and secondary body and chassis weight savings are estimated to be 54% and 14.5% of primary savings, respectively, 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 total weight savings estimated here is somewhat lower than other recent estimates (Malen and Reddy 2007; Saad and Malen 2008). Very significant secondary weight savings were expected for the General Motors 1992 Ultralite carbon body structure that weighed 191 kg (compared to the 102 kg body structure in this analysis based on primary weight savings only) and demonstrated a super-lean 635 kg curb weight concept car. Our estimated secondary weight savings are quite close to the industry norm of using 5% secondary weight savings for every 10% primary weight savings.

With the consideration of secondary weight savings, total body and chassis weight savings are estimated to be 57% as shown in Table 2. There will be a decrease in powertrain weight with powertrain resizing, where engine power is estimated to decrease by 30%. The resulting vehicle weight reduction has been estimated to be 35%. 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 

Table 2.  Major Parameters Considered in the Cost-Effectiveness Analysis of the 50% Body and Chassis Weight Reduction Goal
                                       
                                   Parameter
                                       
                                   Baseline
                             50% Body and Chassis
                           Weight Reduction Scenario
Primary Body & Chassis Weight Savings
                                      NA
                                 345 kg (50%)
Secondary Weight Savings
                                       
                                       
                                                             Body & Chassis
                                      NA
                                50 kg (14.5%)*
                                                                     Powertrain
                                      NA
                                    137 kg
                                                                          Total
                                      NA
                                    187 kg
Body & Chassis Weight
                                    692 kg
                                 297 kg (57%)
Powertrain Weight
                                    594 kg
                                 457 kg (23%)
Engine Power
                                    122 kW
                                     85 kW
Final Vehicle Weight
                                    1524 kg
                                 993 kg (35%)
Combined Fuel Economy 
                                    23 mpg
                                   28.3 mpg
Fuel Price 
                                   $3/gallon
Vehicle Lifetime Operation
                                 120,000 miles
Note: % values within parenthesis indicate savings with respect to baseline steel;
*% savings based on total primary body and chassis weight savings

mass (EEA 2001). Combined vehicle fuel economy would increase from the baseline value of 23 mpg to 28.3 mpg with the 50% body and chassis weight-reduction goal.

2.2 Cost Estimation Methodology

As with the earlier studies (Das 2008 and Das 2009), 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 50% 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) 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. Several studies have used this cost model 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 varies 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 $3.00/gallon, based on the latest energy outlook (EIA 2010). 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 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 68% has been assumed in our case of carbon-FRPMC body structure, i.e., BIW and panels. 

The production economics in this assessment are based 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 commercial grade pricing estimates of $17.60/kg ($8/lb), rather than the optimistic $11.00/kg ($5/lb) target price for the ongoing DOE ALM R&D efforts (considered later as a part of the sensitivity analysis), 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 2 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 $2,690/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 3. The costs represented in Figure 3 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. Body structure cost in this figure is based on the material pricing 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 $17.60/kg. 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 less than 25,000 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 25K-50K. The current estimate is consistent with most past studies indicating cost parity of carbon-FRPMC with conventional baseline steel structure at a production volume in the range of 5,000-35,000 at carbon fiber prices of $11-$17.50/kg (Kang 1998 and Fuchs 2008). Fuchs (2008) estimate of a 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. However, another study indicates the cost-effectiveness of a directed carbon fiber preforming closure panel to be between 500-9,000 annual part production volume (Turner et al. 2008). Similarly, the recently completed European superlight-car project shows a 36% body-in-white weight reduction potential but at a cost penalty of $705 at a daily production volume of 1,000 vehicles (VGR 2008). The cost sensitivities of steel and aluminum structures are quite similar to each other in terms of the curve slope, but they are offset by the material price difference and some increased processing costs. `As also has been observed earlier, the cost sensitivity 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 2. Carbon-FRPMC Body Structure Cost Sensitivity to
                           Annual Production Volume

       Figure 3. Lightweight Material Body-In-White Cost Sensitivity to
                           Annual Production Volume
                                       
                                       
                                       

                                       
   Figure 4. Magnesium Chassis Component Cost Sensitivity to Material Price

Figure 4 shows the per-part cost sensitivity to magnesium casting price for four different magnesium chassis components considered under the carbon-FRPMC scenario based on part weight used in a mid-size vehicle as shown under the baseline scenario in Table 1. Note that the part cost estimates for the base price of $4.44/kg for magnesium alloy ingot price is also shown. The cost estimates for the magnesium cradle includes not only casting cost, but also melting, scrap recovery, machining, and corrosion protection. Cost estimates of magnesium braking and steering systems were made by adding the estimated cost of replaced magnesium 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 chassis magnesium components are based on the recently developed chassis cost relationships using the available EEA estimates (Ibis 2008 and EEA 2007). These relationships consist of two components, i.e., material and processing, with material cost a function of magnesium alloy ingot price. With the exception of the cradle and steering system, the cost relationships for the remaining magnesium chassis components were not explicitly developed. For these remaining systems, relationships are based on the corresponding aluminum component relationships, which were modified to take into account higher magnesium weight reduction potential and using a multiplicative factor in the material component of the cost relationship to reflect the difference in material prices.

As Figure 4 shows, the higher amount of magnesium substitution in the cradle than in the case of the corner suspension causes the former component to be more sensitive than the latter one to magnesium alloy ingot prices. The sensitivity of steering and braking system costs to magnesium alloy ingot pricing is not significant since the magnesium components contributes less than 10% of total system weight in each case. Estimated cost for the steering system is about 1.5 times more than the braking system cost, although the mass relationship between them is quite contrary. The cost of cast magnesium wheels (not shown on this figure) are based on 15" wheels, and new relationships were developed using the same procedure as outlined above. It reflects current material pricing and processing technology improvements and also includes tire costs. It has been assumed to have 20% price premium for processing 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 50% 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 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 a  $373/vehicle increase in retail price and a $1,212/vehicle life cycle cost savings assuming a fuel price of $3.00/gallon and carbon fiber price of $8.00/lb. The increase in vehicle

                                       
           Figure 4. Estimated Cost Savings of 50% Body and Chassis
                           Weight Reduction Scenario

retail price is mainly due to the body system cost increase of about $1,424, the result of the higher cost of carbon unibody structure. The assumption of significant weight reduction potential of 68% has moderated the body-in-white price increase. The cost savings due to downsizing the powertrain and chassis is not sufficient to lower the vehicle retail price. However, the 50% weight reduction goal can be achieved with a life cycle cost savings because the fuel economy benefits more than offset the small vehicle retail price increase. The life cycle saving occurs even though a number of operation cost categories (e.g., financing, insurance, and local fees) are functions of vehicle retail price. Magnesium use in chassis components does not result in much change in the overall chassis system cost as component sizes are reduced considerably to meet the overall body and chassis weight reduction goal. Since the retail price difference is so small, the fuel price was found to adversely affect life cycle cost effectiveness only if fuel price dropped below $1.50/gallon. It is estimated that if the price of magnesium used in chassis components is reduced from the baseline price of $4.44/kg to $3.85/kg and carbon fiber price is reduced from the baseline price of $17.60/kg to DOE's long-term target value of $11.00/kg, the cost-effectiveness at the vehicle retail price level could be achieved, while the assumed gasoline price of $3.00/gallon remains. Unless the carbon fiber price drops to about $2.20/kg while the fuel price remains at $3/gallon, carbon fiber price alone cannot provide the vehicle retail price equivalence (as shown in Figure 5). For carbon-FRPMC to achieve cost-effectiveness at the vehicle retail price level, only less-than-significant material price decreases in several lightweight materials in combination would be necessary. 

 Figure 5. Carbon Fiber Price Sensitivity to Vehicle Retail Price Difference 

An alternative 50% body and chassis weight reduction scenario was also considered. In this alternative the weight reduction potential in body structures is assumed to be around 60%, achievable based on the current technology today. In order to achieve the overall 50% primary weight savings goal, the analysis includes material substitutions in two interior body components, i.e., seat frames and instrument panel, both components in which magnesium use has been successfully commercialized. Both of these magnesium components have been successfully implemented by Jaguar, and magnesium seating applications occur in several vehicle models such as Hyundai Azera, Mercedes Benz SLK 350, Acura RL, and Lexus LS. Meridian Technologies, Inc. is currently producing some of these components, such as steering column brackets and instrument panels, at the rate of 3 and 2.5 million parts per year, respectively. It is estimated that magnesium use would cause a weight reduction of 55% and 33% for seat frames and instrument panel, respectively, with the corresponding cost premiums of 45% and 56%, respectively (Greer 2010 and EEA 2007). 

Table 3 shows the estimated weight savings differences between the original 50% weight reduction scenario and this alternative "Mg Interior" scenario. Vehicle mass decreases as secondary body and chassis mass savings increase from 14.5% in the original 50% weight reduction scenario to 16.8% in the "Mg Interior" scenario. The increased secondary weight savings results not in the interior components themselves, but in the affected body and chassis components, particularly the body-in-white. For example, secondary weight savings for body-in-white was found to be 14 kg and 19 kg for the original and new 50% body and chassis weight reduction scenarios, respectively. Under the "Mg Interior" scenario, the final vehicle weight decreases 9 kg and fuel economy improves 0.1 mpg. Due to more extensive use of the relatively high priced magnesium ($4.44/kg) components, cost equivalence is not achieved at either the vehicle retail price or life cycle cost level. It is estimated that the vehicle life cycle cost spremium would be  $131/vehicle, compared to $1,212/vehicle savings obtained under the original scenario.

Table 3.  Estimated Major Parameters of the Cost-Effectiveness Analysis of the 50% Body and Chassis Weight Reduction Goal Scenarios, including Mg Interior Scenario
                                       
                                   Parameter
                                       
                                   Baseline
                             50% Body and Chassis
                           Weight Reduction Scenario
                             50% Body and Chassis
                           Weight Reduction Scenario
                                  Mg Interior
Primary Body & Chassis Weight Savings
                                      NA
                                 345 kg (50%)
                                 345 kg (50%)
                                                       Secondary Weight Savings
                                       
                                       
                                       
                                                             Body & Chassis
                                      NA
                                 50 kg (14.5%)
                                 58 kg (16.8%)
                                                                     Powertrain
                                      NA
                                    137 kg
                                    138 kg
                                                                          Total
                                      NA
                                    187 kg
                                    196 kg
Body & Chassis Weight
                                    692 kg
                                 297 kg (57%)
                                 289 kg (58%)
Powertrain Weight
                                    594 kg
                                 457 kg (23%)
                                 456 kg (23%)
Engine Power
                                    122 kW
                                     85 kW
                                     84 kW
Final Vehicle Weight
                                    1524 kg
                                993 kg (34.8%)
                                984 kg (35.4%)
Combined Fuel Economy
                                    23 mpg
                                   28.3 mpg
                                   28.4 mpg
Vehicle Retail Price Savings
                                      NA
                                     -$373
                                    -$1,200
Vehicle Life Cycle Cost Savings
                                      NA
                                    $1,212
                                     -$131

4.0 Conclusions

Cost-effectiveness of ALM's 2010 goal to reduce body and chassis weight in light duty vehicles by 50% 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 the earlier 1990s Partnerships of a New Generation Vehicle target and the recently expressed intention of the Japanese government to mass-produce a cost-effective, recyclable carbon fiber vehicle and use it to achieve a 40% reduction in cars' weight by the middle of the next decade (Brooke 2009). The lightweight material substitution options considered here focused on carbon-FRPMC for body systems and magnesium for chassis components to achieve the weight reduction goal. Among potential lightweighting materials, carbon-FRPMC has the greatest weight savings potential. An alternative scenario to achieve the desired weight reduction goal included more extensive magnesium use coupled with less weight savings potential for carbon-FRPMC. The analysis also considered the effect of the 50% primary weight savings on all vehicle components that can be resized while maintaining the same level of vehicle performance with the reduced vehicle weight. These 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 57%, whereas the final vehicle weight savings of 35%.

Cost-effectiveness of the 50% 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.

With the consideration of powertrain resizing and secondary body and chassis mass savings, the carbon-FRPMC lightweight material vehicle option is cost-effective in meeting the ALM 50% body and chassis weight savings goal from the life cycle cost perspective if current gasoline prices continue. The slightly higher vehicle retail price -- an increase of $373 -- results mainly from using the carbon-FRPMC body system which is $1424 more expensive than the baseline system. The body system's higher cost is mostly offset by the powertrain and chassis savings. The higher vehicle retail price does affect some of the operation cost categories such as financing, insurance, and local fees which are functions of vehicle retail price. The effect, however, is outweighed by fuel efficiency and the resulting fuel cost savings at the life cycle level. The vehicle retail price is estimated to be only $373 higher than baseline since the consideration of secondary weight savings significantly reduces the final vehicle body weight to 993 kg. 

Because the estimated vehicle retail price premium is relatively small, only small decreases in some combination of various lightweight material prices would be required to achieve the cost-effectiveness goal at the level of vehicle retail price -- the primary consideration of OEMs for determining the viability of any new vehicle technology. Magnesium and carbon fiber prices need to be at around $3.85/kg and $11.10/kg, respectively for the lightweight vehicle to be cost-effective at the retail price level. The material prices assumed in the analysis are $17.60/kg for carbon-FRPMC and $4.44/kg for magnesium. However, the volatile nature of both material prices and fuel price could affect life cycle cost equivalence. The extent of secondary mass savings is an important consideration in vehicle price and life cycle cost. This analysis employs a conservative estimate of secondary mass savings compared to some recent estimates in the literature. An alternative scenario that uses more magnesium to account for smaller (60%) weight savings for carbon-FRPMC finds that the relatively higher magnesium price would result in higher vehicle retail price and the reduce life cycle cost savings.

Findings in this analysis are consistent with earlier findings that vehicles with high carbon-FRPMC are more expensive than baseline vehicles. However, with the significantly lower cost of commercial grade carbon fiber available today and the high level of weight reduction offered by carbon-FRPMC, the material is largely competitive. Also carbon-FRPMC technology is suited mainly to low annual production volume, and a reduction in carbon fiber price would help to a large extent to improve its viability. 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). 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, which has been considered only in a few of the latest studies and would be critical in the successful commercialization of the lightweight materials technology (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. A recent cost assessment of vehicle mass reduction using a synergestic vehicle teardown approach indicates that a total 20-40% vehicle mass reduction can be achieved without any powertrain weight savings consideration (LEI 2010). Similarly, a recent review article on trends related to automobile mass reduction technology also indicates that advanced vehicle mass optimization techniques such as use of a diverse mix of materials could yield vehicle mass reductions of 30% or greater but would involve some additional costs and manufacturing process modifications (Lutsey 2010). Overall vehicle cost impacts have been estimated to be minimal, only 3% higher even in the 40% mass reduction case, with an extensive use of aluminum and magnesium in body structure components, close to 150 lbs/vehicle. With a higher lightweighting goal, reduced material cost become more critical because it is such a large share of the total part cost particularly in low production-volume manufacturing processes. Accordingly, current foci of DOE's lightweight materials program are the development low cost carbon fibers from alternative inexpensive renewable resources and high-volume processing of composites.

                                  REFERENCES
                                       
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Berger, L. and Jaranson, J. (2009). "Automotive Composites Consortium Focal Project 4," FY 2007 Progress Report for Lightweighting Materials, Vehicle Technologies Program, U.S. Department of Energy, Washington, DC, Available at: http://www1.eere.energy.gov/vehiclesandfuels/resources/vt_lm_fy07.html, accessed on 5/22.

Boeman, R. G. Johnson, N. L (2002). "Development of a Cost Competitive, Composite
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Brooke, L. (2009). "A Featherweight Future," Automotive Engineering International, Vol. 117, No. 5, May, pp. 24-26

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). "Lightweight Opportunities for Fuel Cell Vehicles," SAE paper no. 2005-01-0007, the Society of Automotive Engineers, Warrendale, PA.

Das, S. (2008). "Cost-Effectiveness of a 25% Body and Chassis Weight-Reduction Goal in Light-Duty Vehicles," draft report, Oak Ridge National Laboratory, Oak Ridge, TN, Aug.

Energy and Environmental Analysis, Inc. (EEA) (2001). "Technology and Cost of Future 
   Fuel Economy Improvements for Light-Duty Vehicles," draft report for National Academy of Sciences, June 4.

Energy and Environmental Analysis, Inc. (EEA) (2007). "Analysis of Light-Duty Vehicle Weight Reduction Potential," draft final report submitted to the U.S. Department of Energy, Office of Policy, Arlington, VA, July.

Energy Information Administration (EIA) (2010). "Annual Energy Outlook 2010 with Projections to 2030: Early Release Overview (Summary Reference Case Tables), http://www.eia.doe.gov/oiaf/aeo/index.html, accessed on 3/17/10.

Feraboli, P. and A. Masini. (2004). "Development of Carbon/Epoxy Structural Components for a High Performance Vehicle," Composites: Part B, Vol. 35, pp. 323-330.

Fuchs, E. R. H., F.R. Field, R. Roth, and R.E. Kirchain. (2008). "Strategic Materials Selection in the Automobile Body: Economic Opportunities for Polymer Composite Design," Composites Science and Technology, Vol. 68, pp. 1989-2002.

Greer, D. (2010). Meridian Lightweight Technologies, Plymouth, MI. Personal communication with Sujit Das, Oak Ridge National Laboratory, Oak Ridge, TN, Apr. 2.

Ibis Associates, Inc. (Ibis) (2007).  "Technical Cost Model Development for a Structural Composite Underbody: Supporting USCAR-ACC Composite Structures Program," Waltham, MA.

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Ibis Associates, Inc. (Ibis) (2009a).  "Data Document: ORNL Automotive System Cost Model," Waltham, MA, April 9.

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Ibis Associates, Inc. (Ibis) (2009c). "Technical Cost Model Development: Fiber and 
   Process Preforming Alternatives," presentation made to the USCAR  -  ACC Composite Structures Program, Mar.

Iobst, S. Berger, L. Fernholz, K. Dahl, J. and Smith G. (2007). "Fabrication of the Automotive Composites Consortium Carbon Fiber B-Pillar," International SAMPE Symposium and Exhibition (Proceedings), v 52, SAMPE'07: M and P  -  From Coast to Coast and Around the World, Conference Proceedings, 2007, 11p.

Long, S. Xu, S. and Cao, H. (2005). "Technical Economic Considerations for Production and Application of Mg Castings in China," Materials Science Forum, Vols. 488-489, pp. 909-914, June.

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   AutomobileMass-Reduction Technology," report prepared for California Air Resources Board, Institute of Transportation Studies, University of California, Davis, May.

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   prepared for the FGPC_Mass Compounding Project Team, Auto/Steel Partnership, Southfield, MI, Dec. 26.

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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