<div class="htmlview paragraph">This paper describes a computer study made by the General Motors Corp. Research Laboratories to determine what percentage of the energy supplied to the axle of a passenger car is available for recovery through regeneration. Several weight classes of passenger cars were studied using three driving schedules-city, suburban, and highway. For each vehicle run in accordance with the prescribed driving schedules, two ratio percentages were obtained: (1) the ratio of energy available for recovery to the total energy supplied to the axle, and (2) the above ratio modified by assumed efficiencies in the propulsion and regeneration systems.</div>