The U.S. Postal Service and the Department of Energy have jointly developed and installed a flywheel system in a 1/4 ton electric postal delivery vehicle. The completed vehicle is undergoing test and evaluation. Electric vehicles have the advantage over existing internal combustion engine vehicles of producing minimum pollution and requiring no oil based fuels. Preliminary test results show that adding a flywheel can significantly improve performance and increase the potential application of the electric vehicle for postal delivery service without an increase in energy consumption.