(1) Gasoline and diesel fuel for gasoline- or diesel-powered automobiles; or
(2) Electrical energy for electrically powered automobiles; or
(3) Alcohol for alcohol-powered automobiles; or
(4) Natural gas for natural gas-powered automobiles; or
(5) Liquid Petroleum Gas (LPG), commonly referred to as “propane,” for LPG-powered automobiles; or
(6) Hydrogen for hydrogen fuel cell automobiles and for automobiles equipped with hydrogen internal combustion engines.
40 CFR § 600.002
The following definitions apply throughout this part: