A propulsion system for use in a hybrid vehicle, the propulsion system includes an internal combustion engine, an electric motor/generator operatively coupled to the internal combustion engine, an electric storage medium, and a propulsion system controller for actuating the propulsion system. The propulsion system controller varies the operating conditions of the electric motor/generator system in response to operating conditions of the vehicle. The propulsion system controller further varies the operating conditions of the electric motor/generator during an engine cranking sequence.