Gas Type by Car: Regular, Premium, Diesel or E85 / Audi / S4Audi S4 Gas type by year YearGas type2025Premium2024Premium2023Premium2022Premium2021Premium2020Premium2019Premium2018Premium2016Premium2015Premium2014Premium2013Premium2012Premium2011Premium2010Premium2009Premium2008Premium2007Premium2006Premium2005Premium2004Premium2002Premium2001Premium2000Premium Source: U.S. EPA / DOE fuel economy data (fueleconomy.gov).