Methodologies were developed and applied to project (1) motor vehicle fuel demand, (2) air quality improvements through emission reductions, and (3) the effect of stringent vehicle emission controls on energy consumption. Motor gasoline demand for both the U. S. and Canada is projected to peak about 1980 at about 2% above the current level, followed by a gradual decrease through 1990. However, total U. S. motor fuel use will increase through 1990 due to increasing diesel fuel demand. Ozone air quality projected from HC and NOx emissions shows more improvement resulting from control of other sources than from further tightening of vehicle emission standards. Vehicle emission standards significantly more stringent than the 1975 Canadian level increase energy consumption by as much as 20% at the 1981 U. S. level. Maintenance of the current emission standards in the U. S. could allow sufficient future improvements in gasoline consumption to cause total motor fuel use to decrease after 1982.