 While driving , after the Volt battery has dropped to a predetermined threshold from full charge , a small naturally aspirated 1 @.@ 4 L 4 @-@ cylinder gasoline fueled internal combustion engine ( Opel 's Family 0 ) with approximately 80 hp ( 60 kW ) , powers a 55 kW generator to extend the Volt 's range . The vehicle also has a regenerative braking system . The electrical power from the generator is sent primarily to the electric motor , with the excess going to the batteries , depending on the state of charge ( SOC ) of the battery pack and the power demanded at the wheels . 
