Highway mpg is one of three ratings the United States Environmental Protection Agency (EPA) uses to determine a car’s fuel economy. The EPA calculates a vehicle’s highway, city, and combined fuel efficiency based on the number of miles driven per gallon of gasoline in each scenario. If the EPA rates a car at 28 highway mpg, the estimate predicts the car can travel 28 miles per gallon of fuel consumed during highway driving. Highway mpg is usually the most efficient of the three ratings.
The EPA determines these ratings primarily based on manufacturers’ self-reported results obtained from testing in laboratory conditions. Individual results may vary based on driving habits and real-world situations. Excessive speed, weather or traffic conditions, use of climate controls, extra cargo weight, and other factors may impact highway mpg.
