Electroncally controlled shift-on-the-go transmission

An auxiliary transmission in series with a first automotive transmission adds extra gears through an underdrive feature, which may be manually controlled by an operator or automatically controlled by a computer or controller. The extra gears are useful in matching the output torque of the engine and the transmission to the load on the automobile or vehicle powered by the transmission, and thereby improves fuel economy and transportation performance. The transmission may be installed as factory equipment, or may be added later, such as an after-market or dealer-installed option.