Abstract: A method for improving economy and performance in the operation of internal combustion engines of motor vehicles includes the steps of (a) providing on the motor vehicle a confined supply of alcohol, (b) pressurizing the confined supply of alcohol with engine exhaust gases, (c) passing a controlled stream of alcohol from the confined supply to an enclosure defining an upper zone and a lower zone to maintain a volume of liquid alcohol in the lower zone, (d) charging a stream of air into the volume of the alcohol to vaporize a portion thereof and form vaporized alcohol in the upper zone, (e) causing pressure contained within the enclosure to discharge a stream of the vaporized alcohol from the upper zone of the enclosure into the air intake manifold of the engine, (f) baffling the stream in its passage from the enclosure to the air intake manifold and (g) causing the stream of the vaporized alcohol to mix with the air passing in the manifold for subsequent mixture with the primary gasoline fuel.