This is similar to a hybrid vehicle (HEV) but with a larger battery that can be plugged into a power source such as an electrical outlet to recharge. The PHEV (also known as “Extended Range Electric Vehicle” or EREV) has the advantage of all-electric operation in addition to hybrid operation. Under all-electric operation, the drive train is powered exclusively by the battery. If more power is needed the gasoline ICE starts automatically to assist. Regenerative braking is still employed to recharge the battery. If the plug-in battery is depleted, the vehicle operates as a conventional HEV.
The Chevy Volt is the first production EREV and the plug-in Prius will be available in the summer of 2012. The Chevy Volt has a unique drive train with a four-cylinder ICE generator. The generator is not needed to drive the electric motor until the battery has been discharged after about thirty-five to forty miles. General Motors dubs the Volt an Extended Range Electric Vehicle since it starts off all-electric and the gas generator kicks in only when needed to extend the range. Hawaiian Electric Company has had use of several Chevy Volts as part of two demonstration projects.