m5 hybrid, is an extended-range vehicle, using a combination of engine and motor, tire drive is only responsible for the motor, the internal combustion engine is only used to generate electricity, this design on the one hand can meet the needs of long-distance endurance, so that the battery life of electric vehicles more than 1000 kilometers, on the other hand, the internal combustion engine has been in the highest thermal efficiency of low speed range, saving fuel. However, the problem is that the weight of the vehicle increases, and controlling the fuel consumption of the internal combustion engine and controlling the weight of the vehicle are two difficult points