This paper presents the modelling, design, and optimisation of the powertrain of a hybrid fuel cell electric vehicle (HFCEV), aiming to minimize consumption and thus maximising energy efficiency. The vehicle is the prototype “IDRAKronos” competing at the Shell Eco Marathon race and it is built by the H2Polito team. The hybridisation of a fuel cell electric vehicle (FCEV), through the use of supercapacitors, has a number of advantages, particularly the supercapacitors serve as an energy buffer to satisfy the load peaks requested by the electric motor, allowing a smoother (and closer to a stationary application) working condition for the fuel cell.