A parallel hybrid vehicle includes a heat engine, a transmission including an input and an output, and an electrical device. The transmission input is coupled to the engine and the transmission output is coupled to the electrical device such that substantially all of the torque generated by the heat engine is channeled through the transmission to the electrical device, and a differential, the electrical device coupled to the differential such that during a first mode of operation the electrical device functions as a motor to receive substantially all the torque generated by the engine through the transmission, and such that during a second mode of operation the electrical device functions as a generator to receive substantially all the torque generated by the vehicle through the differential. A method of retrofitting a vehicle is also provided.