Gas Type by Car: Regular, Premium, Diesel or E85 / Chevrolet / CobaltChevrolet Cobalt Gas type by year YearGas type2010Regular2009Regular2008Depends on engine: premium or regular2007Depends on engine: premium or regular2006Depends on engine: premium or regular2005Depends on engine: premium or regular Source: U.S. EPA / DOE fuel economy data (fueleconomy.gov).