The Clean Air Act requires EPA to regulate fuels and fuel additives for use in motor vehicle, motor vehicle engine, or nonroad engine or nonroad vehicle if such fuel, fuel additive or any emission products causes or contributes to air or water pollution that may endanger the public health or welfare. EPA must also address emission products of such fuel or fuel additives that may impair any emission control devices used on vehicles or engines to reduce harmful emissions. 

Gasoline regulations are under 40 CFR Part 80 (“Regulation of Fuels and Fuel Additives”): subparts A (general provisions, applying to all 40 CFR Part 890 fuels programs), B (controls and prohibitions), C (oxygenated gasoline), D & E (reformulated gasoline), G (detergent gasoline program), H & O (gasoline sulfur) and J & L (gasoline toxics).