Abstract: A method for transmitting power to the wheels of a motor vehicle includes driveably connecting an output of a transmission to a first set of wheels, varying the magnitude of torque transmitted to an input of a differential mechanism, varying the speed of the input of the first differential mechanism, and driveably connecting the differential mechanism to the wheels of a second wheel set.

Abstract: A system and method for managing a powertrain in a vehicle determines a number of vehicle conditions, and compares them to predetermined conditions to determine whether a secondary axle of the vehicle should be automatically connected to or disconnected from the powertrain. In general, if the speed of the vehicle is above some predetermined speed threshold, the secondary axle is disengaged to increase fuel economy. Conversely, if the speed of the vehicle is below some predetermined threshold, the secondary axle is typically engaged to help maximize the capture of regenerative braking energy during a braking event. Additional vehicle conditions may be examined, and exceptions to the general rule utilized, to further enhance the control strategy.