A low-pollution steam-powered automobile using a reciprocating piston expander was built and tested for the California Clean Car Project. The performance test results of the automobile and the powerplant are presented herein. The primary test goals which have been successfully demonstrated with the current vehicle are low exhaust emissions and low noise levels. Areas that require improvement in a next-generation vehicle include fuel economy, acceleration, power, reliability, and start-up time. Plans for improving the vehicle powerplant are discussed briefly.