Liters per 100km (L/100km) is the inverse fuel efficiency metric used in Europe and Australia, measuring how many liters of fuel a vehicle consumes over 100 kilometers. Lower numbers mean better efficiency — a car rated at 5 L/100km uses less fuel than one rated at 8 L/100km. This is the inverse of km/L: L/100km = 100 / km/L.

Miles per gallon US (mpg) measures how many miles a vehicle can travel on one US gallon (3.785 liters) of fuel, the standard efficiency metric in the United States. US EPA fuel economy ratings display city and highway mpg figures for every new vehicle. One US mpg equals approximately 0.425 km/L or about 23.52 L/100km.