Gasoline is emitted from automobiles as uncombusted fuel and via evaporation. Volatile organic compounds (VOC) from gasoline are at higher levels in roadway air than in the surrounding ambient atmosphere and penetrate into automobile cabins, thereby exposing commuters to higher levels than they would experience in other microenvironments. Measurements of VOC concentrations and carbon monoxide were made within automobiles during idling, while driving on a suburban route in New Jersey, and on a commute to New York City. Concentrations of VOC from gasoline were determined to be elevated above the ambient background levels in all microenvironments while VOC without a gasoline source were not. The variability of VOC concentrations with location within the automobile was determined to be smaller than inter-day variability during idling studies. VOC and carbon monoxide levels within the automobile cabin differed among the different routes examined. The levels were related to traffic density and were inversely related to driving speed and wind speed. Overall, daily VOC exposure for gasoline-derived compounds during winter commuting in New Jersey was estimated to range between 5 and 20% and constituted between 15 and 40% of an individual's daily exposure based on comparison to urban and suburban settings, respectively. VOC exposure during commuting in Southern California was estimated to range between 15 and 60%.