Gasoline is the fuel designed for spark-ignition internal combustion engines. Conventional gasoline is a mixture of compounds, called hydrocarbons, derived from petroleum crude plus a small amount of a few additives to improve its stability, control deposit formation in engines, and modify other characteristics.Gasoline is the fuel designed for spark-ignition internal combustion engines. Conventional gasoline is a mixture of compounds, called hydrocarbons, derived from petroleum crude plus a small amount of a few additives to improve its stability, control deposit formation in engines, and modify other characteristics.