Gas Type by Car: Regular, Premium, Diesel or E85 / Mazda / 6Mazda 6 Gas type by year YearGas type2021Regular2020Regular2019Regular2018Regular2017Regular2016Regular2015Regular2014Regular2013Regular2012Regular2011Regular2010Regular2009Regular2008Regular2007Depends on engine: regular or premium2006Depends on engine: regular or premium2005Regular2004Regular2003Regular Source: U.S. EPA / DOE fuel economy data (fueleconomy.gov).