To amend section 211 of the Clean Air Act to modify the provisions regarding the oxygen content of reformulated gasoline and to improve the regulation of the fuel additive, methyl tertiary butyl ether (MTBE), and for other purposes.

Amends the Clean Air Act to authorize the Administrator of the Environmental Protection Agency to waive oxygen content requirements for reformulated gasoline upon petition of a State.

Permits the Administrator to control or prohibit the use of any oxygenate (including methyl tertiary butyl ether (MTBE)) as a fuel or fuel additive if the oxygenate contributes to contamination of drinking water which may be anticipated to endanger public health, welfare, or the environment.

Caps the annual volume of MTBE manufactured or introduced into commerce as a fuel or fuel additive, beginning in 2005, at the average annual volume estimated to have been manufactured or introduced into commerce in 1986 through 1991.

Grants States certain authority to prescribe and enforce controls on the use of MTBE as a fuel additive.

Directs the Administrator to establish regional performance standards to ensure that levels of reductions of toxic air pollutants achieved under the Reformulated Gasoline Program are maintained in areas where the oxygen content requirement is waived.

Requires any regulation or modification of fuel properties made by this Act to take into account the need to provide lead time for refinery and fuel distribution system modifications necessary to assure adequate fuel supply for all States.