Vehicles with electric propulsion systems are increasingly more often equipped with solutions that improve their drive system’s efficiency. The latest vehicle model with a fuel cell hybrid system – Toyota Mirai was used in this experiment. The design of this vehicle is similar to that of hybrid vehicles in many aspects. However, new fuel cell technologies are being developed for automotive use, including compressed hydrogen tanks and control systems. The article presents an analysis of a fuel cell operation during vehicle start-up and driving, with particular emphasis on the hydrogen injection strategy of the three fuel injectors used in the fuel cell. The fuel cell interaction with the high-voltage battery has also been characterized. It has been shown that increase in the electrical supply voltage of the vehicle’s electric motor can be observed at high torque values of the electric motor. The maximum voltage gain – approximately three times (up to about 650 V) – allows for double the torque of the drive system compared to the standard value.