Many experimental models of gas turbines have been built for vehicle propulsion, and indications are that production models may be available within the next decade. Special effort has been devoted in recent years to improving the fuel consumption by adding heat exchangers to the originally proposed simple-cycle gas turbines. If they are to be competitive with reciprocating engines, gas turbines must not only be equal or better in performance, but equal or lower in cost. This would require manufacture in large quantities, and it is very likely that the first production models will be in a low-priced high-production automobile.