A coaxial multi-member mechanism for using as the front axle and the rear axle in an electric vehicle is presented to allow the wheels of the vehicle changing the track widths from a wide track to a narrow track or vice versa in vehicle moving condition. The wide track mode is for safer high speed driving and more collision protection from the four wheels. The narrow track is used on the other hand for narrow street and slow speed driving and for easy parking in a narrow space.