Emissions from Catalyst Cars Beyond 50 000 Miles and the Implications for the Federal Motor Vehicle Control Program

High mileage vehicles (in excess of 50,000 miles) contribute more than half of all vehicular emissions. With the new catalytic converter equipped cars, the proportional contribution of these vehicles may be even higher than for pre-catalyst vehicles. Thus a substantial portion of motor vehicle related air pollution may be caused by vehicles not subject to the manufacturer directed provisions of the Clean Air Act. This paper presents a modeling effort based on hypotheses and some preliminary data, and suggests some alternatives to combat this potential problem.