Possible fuel efficiency improvements of light-duty methanol engines are reviewed in comparison to gasoline engines. This comparison outlines improvements resulting from differences in fuel properties and engine configurations. Methanol engines evaluated included those with higher compression and those using lean-burn, stratified charge. Higher compression yields about a 10 percent improvement over gasoline engines. Lean-burn concepts result in 13 percent increases over gasoline engines operated stoichiometrically.
Fuel economy for the California dedicated methanol fleet is evaluated and compared to existing baseline gasoline fuel economy. Data for both carburetted and fuel-injected 1983 Ford Escorts are presented. Fuel economy for the carburetted vehicles used in a variety of fleets ranged from 20.9 to 26.0 mpg on a gasoline equivalent basis. The overall California 500-car fleet average fuel economy is 23.7 mpg which is slightly less than the adjusted EPA city fuel economy for gasoline Escorts. Average fuel economy for the methanol fuel-injected engines is 29.7 mpg on an equivalent energy basis compared to an adjusted EPA city fuel economy of 25.2 mpg. Both comparisons indicate less gains with methanol than expected based on fuel properties and higher compression.
California's experience with dedicated vehicles pointed out concerns of vehicle range and lack of fueling stations. The concept of flexible fuel vehicles (FFVs) being developed by many manufacturers may be the best transition strategy for introducing methanol, but not necessarily the best strategy to maximize methanol's air quality and energy security benefits. These issues are discussed relative to different FFV concepts.
