Current state periodic motor vehicle inspection (PMVI) programs vary widely both in items inspected and inspection criteria. Many performance parameters not tested could have a significant impact on highway safety. New automotive emissions standards will achieve their goal of reducing air pollution only if periodic inspections are instituted to verify vehicle system performance. Thus, a trend is apparent toward more effective and uniform safety inspection coupled with emissions inspection. Such an inspection is feasible only if inspection automation can provide high throughput, effective testing, and component fault diagnosis. The diagnostic requirement is crucial in protecting the consumer from exposure to a potential ticket to still higher automotive repair bills.