Depending on how much acceleration you ask for the engine in the Qashqai e-Power either idles along charging the battery or raises its revs to directly power a 190PS electric motor connected to the front wheels. The engine needs to be able to deliver enough power to ensure that quick acceleration. It is not the same as the tiny range extender petrol engine in, say, a BMW i3 REx electric car, because that simply exists to charge up a much larger battery pack.