It is thought that adding oxygenated molecules to gasoline mixtures leads to cleaner burning of gasoline and less air pollution. For this reason alcohols (methanol, ethanol) are added to gasoline.

One substance that seems to improve the burning characterisitcs of gasoline is methyl t-butyl ether (MTBE).

See jmol: MTBE (methyl t-butyl ether)

MTBE has turned out to create a serious environmental problem. When it spills and leaches into the ground, it finds it ways into drinking water supplies. It imparts offensive odors and tastes to water.