Divide the number of mpg by 0.6215 to convert to km/g. For example, if your truck gets 17 mpg, divide 17 by 0.6215 to get 27.4 km/g.
Multiply the number of mpg by 1.609 to convert to km/g. For this example, multiply 17 by 1.609 to get 27.4 km/g.
Check your answer with an online conversion website (see Resources). Enter the number of miles per gallon, click "Convert," and the website will show you the equivalent in kilometers per gallon.