Consumers paid an average of $748 extra per car in California in 1990 because of vehicle emission controls required by state law, according to UC Davis researchers. Vehicle emission-control costs added $370 to $2,430 to the purchase price of individual cars and trucks. Based on emission-part prices, the UC Davis study is believed to be the most systematic and thorough analysis of emission-control costs to date. As the United States and other countries enter a new round of vehicle emission reductions, such detailed analyses are needed to determine the most cost-effective way of further reducing emissions, says Dan Sperling, director of the Institute of Transportation Studies at UC Davis. Cost differences among manufacturers show that three domestic manufacturers have the least per-vehicle emission-control costs and European manufacturers the highest emission-control costs. The paper will be presented by Quanlu Wang, an assistant research engineer at the Institute of Transportation Studies at UC Davis, in session No. 241, at 8:30 a.m., Thursday, Jan. 7, at the Hilton.