Baseline fuel economies were determined for one class of vehicles, namely subcompacts. Subcompacts represent one of the most fuel-efficient classes of vehicles and many of the advanced technology vehicles are in this class. Sixty-eight model year 2000 vehicles within this class were averaged (high performance vehicles were eliminated from the data – see Appendix A for the list of vehicles). Using undiscounted fuel economies6 the average fuel economy for the 68 vehicles was 32.26 miles per gallon. To account for real world conditions, this fuel economy were discounted by 15% resulting in a fuel economy of 27.42 mpg. Assuming a 10% improvement in fuel economy between 2000 and 2010, the average baseline fuel economy is 30.16 mpg.
Several of the advanced technologies are super efficient vehicles and should be compared to a super efficient baseline vehicle. This class similar to the Partnership for the New Generation of Vehicles (PNGV). It is expected that this class of vehicles will be 50% more efficient than the typical subcompact, resulting in a baseline fuel economy of 45.2 mpg (on-road estimate). The PNGV program estimates a CAFÉ value of 52 mpg for gasoline vehicles with conventinal drive trains which is consistent with the on road value of 45.2 mpg.
5.3.2 Diesel Vehicles
Only Volkswagen currently produces light-duty diesel vehicles in the United States. Three models of diesel vehicles were compared against their gasoline counterpart, namely the Golf, Jetta, and New Beetle. Using a lower heating value for diesel fuel of 130,800 Btu/gallon, the average fuel economies for the model year 2000 automatic transmission versions of these vehicles were compared, resulted in an EER of 1.37 as shown in Table 5-2. Weight comparisons indicated the diesel vehicles to be about 2% heavier than their gasoline counterparts.
Table 5-2: Diesel Energy Economy Ratio
Diesel Version mpg
Gasoline Equivalent mpeg
Gasoline Version mpg
In a separate analysis, CEC examined 176 European direct-injected diesel vehicles and compared them against 831 European gasoline vehicles of the same class. This resulted
6 The EPA Fuel Economy Guide lists discounted fuel economy results to account for real world driving. Undiscounted values are published at EPA’s Fuel Economy website (. Undiscounted values provide a better comparison among various alternative technologies and fuels.