Vehicle Inspection and Maintenance-The California Program

Current California law requires the implementation of a mandatory annual vehicle emissions inspection and maintenance program in the South Coast Air Basin by 1978. The pilot phase of this inspection program is now in operation in the City of Riverside. This paper evaluates the Riverside program and an alternate program for their abilities to detect gross emitters and provide cost/effective emissions reductions.

A surveillance program was conducted to evaluate the Riverside loaded-mode inspection regime and an alternate idle inspection regime. Emissions and fuel economy tests indicated that there was no significant difference between the two regimes. Each regime resulted in immediate reductions on repaired vehicles of 35-40% in hydrocarbon emissions and 30-35% in carbon monoxide emissions, with no significant change in oxides of nitrogen emissions. There was a small (1-4%) improvement in fuel economy, and the average repair cost was $20-25.

The more sophisticated diagnostic and repair procedures associated with the loaded-mode inspection regime did not result in improved performance of repairs when compared to the simpler and less expensive idle inspection regime. However with average inspection costs of about $5 per car for the loaded regime and $4 per car for the idle regime, both approaches provided cost/effective reductions in hydrocarbon and carbon monoxide emissions. Other studies indicate that similar reductions are possible on catalyst-equipped vehicles, and that the loaded-mode inspection program has the potential to provide significant reductions in NOx emissions on late model vehicles.