Abstract: The present disclosure is related to an improved speed variable transmission system adapted for, in particular, electrically operated vehicle. The system is operated by common manual gear shift. The manual gear shift has a power source made up of a specially designed electric motor having a rotatable outer shell relatively moveable with respect to a core rotor so that the power from the rotatable outer shell and the core rotor of the electric motor can be output respectively to a front and a rear differential gear device, and the vehicle can be powered to move via the differential gear devices. The respective transmission shafts between the electric motor and the front and rear differential gear devices can be selectively locked so that the power from the motor can be selectively varied when output to the differential gear devices thereby the wheels of the automobile can be varied in speed.