This is the “series hybrid” or “range extender” approach and the issue is that all of the engine’s power needs to be converted into electrical power and then ba

This is the “series hybrid” or “range extender” approach and the issue is that all of the engine’s power needs to be converted into electrical power and then back into mechanical power, even when running the traction motor directly off the generator output. This causes significant losses in efficiency which more or less cancel out the gains from being able to optimise the engine for a specific constant speed.