in an EER of 1.21. Thus the range of EERs for future diesel vehicles was assumed to be the same as current vehicles, namely 1.21 to 1.37.
5.3.3 LPG Vehicles
No LPG vehicles are currently availble from major manufactureres. EER values for LPG were estimated from CNG data and prior experience with LPG vehicles.
Several models of compressed natural gas vehicles were compared against their gasoline counterpart as shown in Table 5-3. EERs varied from 0.94 to 1.00 with the average being 0.98. Discussions with vehicle manufacturers have indicated that improvements in technology, such as port injection, will improve CNG fuel economy and should increase EERs as high as 1.08. Weight comparisons for the vehicles listed in Table 5-3 indicate that the CNG vehicles are 7% heavier than their gasoline counterparts.
Table 5-3: CNG Energy Economy Ratios
CNG Version m/100 scf
Gasoline Equivalent mpeg
Gasoline Version mpg
5.3.5 Fuel Cell Vehicles
Prototype hydrogen fuel cell vehicles built by Ford and Daimler-Chrylser have been tested on U.S. driving cycles, but have no direct gasoline equivalent. Steam reformed methanol vehicles and partial oxidation reformer gasoline fuel cells are being tested in the laboratory. Several academic institutions have developed computer models of fuel cell vehicles to predict fuel economy for these technologies. Using this limited data, EERs of 1.50 to 1.74 have been estimated for hydrogen fuel cell vehicles, 1.39 to 1.54 for methanol steam reformed fuel cell vehicles. These estimates are highly speculative and will need to be refined as these technologies become more commercial.
5.3.5 Electric Vehicles
Several models of electric vehicles are currently in production both in the passenger car and light truck classes. Only the light truck and minivan classes have gasoline equivalent vehicles. The passenger car electric vehicles are specialty built vehicles