Gas Type by Car: Regular, Premium, Diesel or E85 / Mercedes-Benz / R-ClassMercedes-Benz R-Class Gas type by year YearGas type2013Premium2012Premium2011Premium2010Premium2009Premium2008Depends on engine: diesel or premium2007Depends on engine: diesel or premium2006Premium Source: U.S. EPA / DOE fuel economy data (fueleconomy.gov).