Vehicle Misfueling in California During 1979

A survey of vehicle refueling practices in California during the gasoline shortage of 1979 indicates that the use of leaded gasoline in catalyst equipped vehicles was occurring at a rate of about 1.6%. This 1.6% “misfueling” rate is lower than has been predicted by the U.S. Environmental Protection Agency and is almost exclusively the result of the refueling that occurs at self-service gasoline pumps. About three-quarters of the misfueled vehicles were apparently operated on leaded gasoline routinely.

Based on the effect that leaded fuel has on the exhaust emission characteristics of catalyst equipped vehicles it is estimated that misfueling in California is increasing hydrocarbon and carbon monoxide emissions by about 4% and 1.6%, respectively from late model passenger cars. The extent to which misfueling will become a greater problem in the future may depend on: (1) the availability of unleaded gasoline, (2) the cost differential between leaded and unleaded gasoline, (3) the tendency toward increased misfueling with increasing vehicle age, (4) the extent to which filler neck designs will be altered to increase the difficulty in modifying the “lead restrictor” so that leaded fuel nozzles can be used, and (5) the existence of inspection programs which identify and cause the correction of misfueld vehicles.