This paper reports a methodology to design a high efficiency fuel cell powertrain. The powertrain equips a prototype car that runs energy-efficient races where the objectives are to go the furthest with the lowest quantity of fuel (Shell Eco Marathon). In the design process, the starting point was the evaluation of the car's energy demand to run on a specified race track by developing a dynamic mechanical model of the car. A dedicated inertial test bench was constructed to reproduce the car's behavior in the laboratory. This was used to determine under which operating conditions an electric motor has to be powered to reach the highest efficiency. The introduction of ultracapacitors was envisaged and, based on efficiency arguments, a drive train arrangement was chosen composed solely of a 500 W PEFC stack, a DC/DC converter operated in a current regulation mode and an electric motor. Final tests of the powertrain revealed the most efficient operating conditions. The present work is the necessary first stage for both the design of the complete powertrain and its detailed energy analysis. It forms the basis for future improvements. (C) 2011 Elsevier Ltd. All rights reserved.