To amend the Clean Air Act to permit the exclusive application of California State regulations regarding reformulated gas in certain areas within the State.

Amends the Clean Air Act to allow reformulated gasoline rules of States for which a certain waiver is in effect (permitting them to enforce State motor vehicle emissions standards) to apply in an ozone nonattainment area in lieu of Environmental Protection Agency-promulgated requirements if the State rules will achieve reductions in the aggregate mass of emissions of toxic air pollutants and the aggregate mass of emissions of ozone-forming compounds at least as great as would result from application of the Federal requirements.