Conventional gasoline vehicle fuel economy. The computer model assumes that the fuel economy of all vehicles increases over time. The baseline fuel economy is projected to increase steadily for conventional gasoline cars as improvements are made to the internal combustion engine (ICE).
We assume that the average fuel economy for the entire light duty vehicle (LDV) fleet of gasoline-powered ICE vehicles, which includes both cars and light duty trucks, vans and SUVs, increases from 20 mpg in 2009 to 34 mpg by 2100. These are the actual on-road fuel average economy estimates for all (non-hybrid) gasoline LDVs, both passenger vehicles and light duty trucks, vans and SUVs, old and new, not the historical EPA estimated fuel economy of new cars which is always higher than actual performance. The increased fuel economy for HEVs, PHEVs and FCEVs is accounted for separately, as described below.
Alternative vehicle fuel economy. We assume that each of the alternative vehicles have fuel economies that are a fixed factor times that of the internal combustion engine vehicle (ICV), since much of the improved fuel economy is due to reduced aerodynamic drag, lower body weight and lower rolling resistance which benefits all vehicles. The improvement multiplying factors for the key alternative vehicles were derived by averaging four reports for the literature:
- Hybrid electric vehicle: 1.49 times higher fuel economy than ICV
- Plug-in hybrid electric vehicle (when running on gasoline): 1.49 times
- Biofuel HEV & PHEV (when running on biofuel): 1.51 times higher
- Hydrogen fuel cell EV: 2.4 times higher [Note: this 2.4 fuel economy improvement was based on an average of various estimates from the literature (see box below); However, we now have a real-world direct comparison of an internal combustion engine vehicle and a FCEV: theToyota Highlander SUV has a rated fuel economy of approximately 22 mpg. The fuel cell version of the Highlander was certified by DOE national lab engineers at 68.3 miles per kg of hydrogen, which is equivalent to 69.1 mpgge, which is 3.1 times the fuel economy of the conventional (non-hybrid) Highlander SUV. So the 2.4 times fuel economy improvement used in this model may be too conservative, based on this first real-world comparison.]