Gasoline that has been formulated in a way that is designed to reduce carbon monoxide from automotive exhausts. Oxygenates are either alcohols or ether compounds, added to gasoline.

A number of American communities, with severe air pollution problems, now mandate use of oxygenated fuels. Oxygenated gasoline is particularly in demand during the winter months in areas where weather conditions cause increased air-pollution levels.

Oxygenates increase the oxygen-to-fuel ratio inside an internal-combustion engine. This results in a more complete burning of the fuel, and hence reduces the amount of harmful pollutants released into the air.