The author examines the potential of the gas turbine in alleviating air pollution as a replacement for presently used vehicular reciprocating engines. Automobiles receive particular emphasis because of the magnitude of their contribution to the problem. Emissions of gas-turbine engines are compared with those of gasoline reciprocating engines, and other important characteristics relevant to the problem (such as engine power output, reliability, transmissions, vehicle performance, fuel consumption, and manufacturing cost) are discussed. It is concluded that widespread adoption of vehicular gas-turbine engines can — provided these engines can be produced and operated at costs competitive with those of future reciprocating engines — can virtually eliminate automotive air pollution as a source of serious environmental concern.