Abstract: A family of fuel additives particularly containing certain diamines preferably in combination with certain alcohols, the invention provides compositions of matter which improve the performance of internal combustion engines and provide favorable fuel economies relative to fuels not used with the present additives. Tertiary diamines such as N,N,N',N'-tetramethyl-1,3-propanediamine are added in low concentrations to gasoline, the diamines preferably being mixed with an anhydrous alcohol prior to admixture with gasoline. Particularly effective additives according to the invention also include an admixture of the foresaid mixture with isopropyl and diacetone alcohols.