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.