REAL-WORLD EMISSIONS FROM CONVENTIONAL PASSENGER CARS

It has long been recognized that vehicles emit more pollutants than al lowed under the new car emission standards. Further tightening of the certification standards based on existing test procedures does not dir ectly address the largest sources of emissions. This study attempts to quantify vehicle emissions by source, in order to prioritize future p olicymaking. Several new sets of data are used in conjunction with reg ulatory emission models to characterize the lifetime emissions from th e average Model Year (MY)93 vehicle. Special attention is paid to two of the largest sources of real-world emissions: (1) high-power driving by cars with properly functioning emissions controls, and (2) cars wi th malfunctioning emissions controls. Emissions are projected to MY200 0 and 2010, based on estimates of the effectiveness of recently adopte d and proposed regulatory policies. These new policies are projected t o reduce total emissions substantially.