To produce a gasoline additive effective for improving the burning efficiency of gasoline to prevent the incomplete combustion when mixed to gasoline, realizing the increase of engine power and reduction of fuel cost, suppressing the generation of carbon and decreasing the carbon monoxide concentration in exhaust gas and to provide a gasoline added with the gasoline additive.

This gasoline additive is composed of toluene, methanol, isopropyl alcohol and isopropyl ether. It can be produced by mixing toluene, methanol, isopropylalcohol and isopropyl ether at ratios of 56%, 32%, 6% and 6%, respectively. The objective gasoline is produced by adding the gasoline additive to a gasoline.