The DOE ETV-1 represents one of most advanced vehicles in operation today. Engineering tests are now being conducted by the Jet Propulsion Laboratory in order to characterize its overall system performance and component efficiencies within the system environment. A chassis dynamometer is used in order to minimize the ambient effects and large uncertainties present in track testing. Extensive test requirements were defined and procedures were carefully controlled in order to maintain a high degree of credibility. Test results include an energy flow analysis through the major subsystems and incorporate the aerodynamic and rolling losses under cyclic and various steady speed conditions.