Vehicles registered in the District of Columbia (D.C.) had a higher average fuel economy in 2018 than any state. The average fuel economy of vehicles in each state were calculated by researchers at Argonne National Laboratory using vehicle registration and EPA combined city/highway fuel economy data. D.C. and twenty-four states averaged above 20 miles per gallon (mpg) while the rest of the states averaged from 18.1 to 20 mpg.
Source: Argonne National Laboratory, Affordability of Household Transportation Fuel Costs by Region and Socioeconomic Factors, ANL/ESD-20/11.