Two testing campaigns were performed in Turin by CRF (the Fiat Research Center), and in Rome by ENEA (the Italian National Agency for New Technologies, Energy and the Environment) and the University «ROMA TRE». The work demonstrates the feature of a FC emulator to characterize fuel-cell-propelled drivetrains without employing an expensive PEM fuel cell and it points out how the vehicle fuel consumption, on a specific mission, depends on two fundamental parameters, the accordance of the FC nominal power with the requested power of the mission and the battery State-of-Charge. In the ENEA Research Center «Casaccia», near Rome, the behaviors of PEM Fuel Cells of different sizes (7, 15, 22 kW) were simulated by replacing them with a controlled AC/DC converter, this fuel cell emulator powering a full-scale hybrid drive train. A real hybrid 60-kW FC powertrain was tested at the same time in Turin and the obtained results were used to build the control function for the FC emulator and to validate the results from the powertrain being tested in Rome. This paper shows the experimental test campaign in Rome, and it focuses the sharing of the power fluxes among fuel cell, battery and motor, for different FC power settings and battery energy levels (SOC).