A vehicle's fuel economy directly affects the owner's wallet, which makes comparing the gas mileage of our cars a popular water-cooler topic. A vehicle's gas mileage is also a popular topic when researching cars for purchase. To avoid "comparing apples to oranges," it is sometimes necessary to convert between measurement systems. In the United States, the numbers represent miles per gallon (MPG), but in other parts of the world measures such as miles per litre (MPL) may be used. You may also wish to convert if your odometer reads in miles but you buy gasoline by the litre.
Determine a vehicle's MPL (miles per litre) either from published sources or by calculating it yourself. Divide the number of miles driven by the number of litres consumed to calculate MPL.
Use a calculator or pencil and paper to multiply the MPL value by 3.785, the number of litres in a gallon.
Read the miles per gallon (MPG) value. Example: 6.1 MPL times 3.785 = 23.1 MPG.
Most countries that use the metric system provide fuel economy in litres per 100km. To convert L/100Km to MPG, divide 235.2 by the L/100Km value.