A method of controlling a vehicle powertrain and a corresponding vehicle control system are provided that enable operation in an electric-only operating mode for an extended range by adjusting the threshold minimum state of charge of the battery, i.e., the state of charge of the battery at which the engine will be started to allow the battery charge to be replenished, in accordance with vehicle location. The engine will also be started when the vehicle is within a predetermined distance of a long-term parking location.