Aerojet Liquid Rocket Co. is evaluating the potential of the Rankine cycle engine as a low emission alternative to the internal combustion automotive engine. An organic fluid turbine engine has been designed, fabricated, and tested. A steam turbine engine is being prepared for vehicle road tests. Based upon fuel economy of 10 miles/gal, emissions less than one-fourth of 1975-1976 federal standards have been demonstrated. Performance equivalent to the internal combustion engine without exhaust emission controls appears feasible with further development.