Published in the Proceedings of the
8TH CRC ON-ROAD VEHICLE EMISSIONS WORKSHOP
San Diego, California
April 20-22, 1998

Tom Wenzel
Environmental Energy and Technologies Group
Lawrence Berkeley Laboratory
Berkeley, CA 94720

Marc Ross
Physics Department, University of Michigan
Ann Arbor, MI 48109

Lawrence Berkeley National Laboratory has begun compiling in-use vehicle emissions data generated by state Inspection and Maintenance (I/M) programs, to analyze in-use vehicle emissions and the effectiveness of state I/M programs. Earlier analyses of remote sensing data from California, IM240 data from Arizona, and idle test data from Minnesota indicate that, for a given model year, certain vehicle models have emissions failure rates several times that of the average vehicle. Recent acquisition of multiple years of IM240 and remote sensing data from Arizona allows a comparison of failure rates by vehicle model as measured by different technologies, to determine if the same models are consistently identified as having high in-use emissions. Failure rates by model in Arizona also will be compared with failure rates in other IM240 states, as data become available.

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