Therefore, the choice of vehicle classes for future consideration as part of this assessment of potential fuel economy technologies should focus on vehicle size, weight, interior passenger volume, intended use, and the potential for implementation of next-generation power trains, including hybrid electrics. Based on various factors outlined below, the following classification of light-duty vehicles in the United States was determined by the committee to be an appropriate basis for future technology development and introduction into production.

  1. Two-seater convertibles and coupes—Small vehicles by interior volume whose function is high-performance and handling. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a six-cylinder, four-valve, dual overhead cam engine with intake cam phasing and a 6-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  2. Small cars—Mini-, sub-, and compact cars, standard performance, mostly four-cylinder, mostly front-wheel drive (FWD), including small station wagons. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a four-cylinder, four-valve, dual overhead cam engine with intake cam phasing and a 6-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  3. Intermediate and large cars—Standard performance, mostly FWD, mostly six-cylinder, including large station wagons with less than 0.07 hp/lb of vehicle weight. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a six-cylinder, four-valve, dual overhead cam engine with intake cam phasing and a 4-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  4. High-performance sedans—Passenger cars with greater than or equal to 0.07 hp/lb of vehicle weight that are not two-seaters. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a six-cylinder, four-valve, dual overhead cam engine with intake cam phasing and a 6-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  5. Unit-body standard trucks—Non-pickup trucks with unibody construction and hp/lb of vehicle weight ratios of under 0.055 including crossover vehicles, SUVs, and minivans. Most vehicles employ front-wheel drive. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a six-cylinder, four-valve, dual overhead cam engine with intake cam phasing and a 6-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  6. Unit-body high-performance trucks—Crossover vehicles, SUVs, and minivans with hp/lb of vehicle weight ratios of 0.055 or greater. Most have rear-wheel drive (RWD) or all-wheel drive (AWD) and unibody construction, and most are luxury vehicles. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a six-cylinder, four-valve, dual overhead cam engine with intake cam phasing and a 6-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  7. Body-on-frame small and midsize trucks—Pickups less than or equal to 1,500 lb payload capacity (CEC class 14) and SUVs of up to 175 cubic feet of passenger volume plus cargo volume with RWD or AWD. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: a six-cylinder, two-valve, single overhead cam engine with a 5-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

  8. Body-on-frame large trucks—Pickups of greater than 1,500 lb payload but less than 10,000 lb GVW, and SUVs with 175 cubic feet or greater of passenger plus cargo volume with RWD or AWD, including all standard vans, cargo and passenger. The average 2007 model-year vehicle for this class was developed from EPA (2008a) and has the following characteristics: an eight-cylinder, two-valve, overhead valve engine with a 4-speed automatic transmission. The average vehicle for this class is used as the base vehicle in the estimation of fuel consumption reductions for multiple technologies as discussed later in this chapter.

These eight classes allow an evaluation of similar base vehicles designs, where the vehicle size, baseline chassis configuration, aerodynamic characteristics, vehicle weight and type of drive train (FWD, RWD, and AWD) are similar. This grouping should result in vehicle classes where similar calibration criteria are associated with similar vehicle performance characteristics. A greater number of classes would



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