The main mechanical components of a hybrid car are
the power-control unit (PCU), the generator, the electric
motor(s), the battery, and the gasoline engine. The PCU
manages the optimum combination of gasoline and electric
power. At start-up and when driving at low speeds, the
vehicle is powered purely by the electric motor(s). In this
electric vehicle mode, the car uses no gasoline and produces
zero emissions. As the speed increases, the system
switches from electric to gasoline engine power. At cruising
speeds, the power split device engages planetary gears to
ensure that the gasoline engine not only drives the front