EVAPORATIVE AND EXHAUST EMISSIONS FROM CARS FUELED WITH GASOLINE CONTAINING ETHANOL OR METHYL TERT-BUTYL ETHER

Vehicle tests showed that evaporative emissions were increased significantly by adding 10% ethanol to gasoline, but were increased less by adding 15% methyl tert-butyl ether (MTBE), a gasoline blending component. The quantity of ethanol or MTBE in evaporative emissions was investigated in laboratory tests. Exhaust hydrocarbon, carbon monoxide, and nitrogen oxide emissions from a car without closed-loop fuel control were significantly lower with the ethanol and MTBE fuel blends than with gasoline. For cars equipped with closed-loop carburetors, there were small absolute differences in exhaust emissions among the fuels. Fuel economy and driveability were worse with ethanol and MTBE fuel blends than with gasoline.