Emissions, Fuel Economy, and Driveability Effects of Methanol/Butanol/Gasoline Fuel Blends

The immediate effects of methanol-gasoline blends on vehicle emissions, fuel economy, and driveability were investigated. The addition of a 2:1 mixture of methyl and butyl alcohols to gasoline, to provide a total alcohol concentration of either 10 percent or 18 percent, resulted in higher evaporative emissions, lower carbon monoxide emissions, lower volumetric fuel economy, and poorer driveability. Exhaust hydrocarbon and nitrogen oxide emissions decreased with some cars and increased with others. The closed-loop fuel metering systems, with which some of the test cars were equipped, could not completely compensate for the leaning effect of the alcohols. Consequently, the results of this test program suggest that these alcohol-gasoline blends would not be satisfactory for use in many cars either with or without closed-loop systems.