hot water is transmitted from an automobile &# 39 ; s cooling system to a fuel vaporizer wherein it is utilized to heat gasoline to a vapor state . air is drawn into the fuel vaporizer utilizing carburetor vacuum and is added to the vapor and drawn into the carburetor . vaporized fuel and outside air are mixed in a separate dry vapor section within the vaporizer and the amount of air allowed to enter the fuel vaporizer is controlled utilizing a valve system . in this manner , the fuel - air vapor is more efficiently burned in the engine and improved gas mileage is achieved .