Measuring a vehicle's fuel efficiency means measuring the amount of gas needed to power your vehicle over a given distance. With gas prices rising constantly, fuel efficiency becomes more and more important to consumers and vehicle manufacturers. In the United States, we calculate fuel efficiency using miles per gallon or mpg. Many countries use the metric system, which uses liters instead of gallons. With a simple mathematical calculation, you can convert your mpg to Miles Per Liter.
Use the formula to calculate miles per gallon: miles driven / amount of gas (gallons).
Divide the amount of miles you drove by the amount of gallons of gas you had filled up to find the miles per gallon (mpg). For example, if you drove 150 miles and filled up 5 gallons of gas, it would be 30 miles per gallon.
Divide the mpg you calculated in Step 2 by 3.785 to convert gallons to liters. The conversion equation of 30 miles per gallon/ 3.785 would give you 7.926 miles per liter.
