An electric propulsion system for use with a vehicle including a pair of first wheels, a pair of second wheels, and a gas propulsion system. The electric propulsion system includes a first electric traction motor mounted to one of the first wheels, and a second electric traction motor mounted to the other one of the first wheels. The electric propulsion system includes pair of electric motor controllers each in electrical communication with a respective one of the first or second electric traction motors. Each of the electric motor controllers are also in electrical communication with the system controller and configured to receive vehicle signals from the system controller to control the respective electric traction motors accordingly. Put another way, the pair of electric motor controllers react to vehicle conditions to provide vehicle assist power to the gas propulsion system as needed.