General Motors have said that the 1.4 litre petrol engine in the 2011 Chevrolet Volt will require premium fuel. The Volt hybrid uses an 111kW electric motor as its primary driving force. When the lithium-ion battery pack is used up after 40 miles (65km), the 80bhp petrol engine comes to life to recharge the motor and battery pack, extending the vehicle's range to 300 (547km) miles plus. Combined