The California Legislature conducted an investigation into the low emission properties of steam-powered automobiles, 1972-74. Two steam propulsion systems were built and installed into sub-compact cars suitable for urban driving. The Aerojet Liquid Rocket Co. installed a steam turbine in a Chevrolet Vega, while Steam Power Systems built a piston engine system for a car of special design. The project demonstrated that it is possible to reduce exhaust emission levels to less then those required by the 1978 Federal standards. Road performance was adequate for urban-suburban driving. Fuel consumption was higher than comparable internal combustion-powered vehicles. Guidelines for future improvements are given.