Gas Type by Car: Regular, Premium, Diesel or E85 / Buick / LaCrosseBuick LaCrosse Gas type by year YearGas type2019Regular2018Regular2017Regular2016Regular (flex-fuel E85 engine available)2015Regular (flex-fuel E85 engine available)2014Regular (flex-fuel E85 engine available)2013Regular (flex-fuel E85 engine available)2012Regular (flex-fuel E85 engine available)2011Regular Source: U.S. EPA / DOE fuel economy data (fueleconomy.gov).