How to Calculate Your Car's Fuel Consumption

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Author's Note: How to Calculate Your Car's Fuel Consumption

I realized in writing this that I had never calculated my car's fuel consumption. I know that I fill up every 250 miles or so, and that at my last fill-up, I purchased 12.38 gallons of gas (the receipt was still stuffed in the console cubbyhole). So that's 250 miles divided by 12.38 gallons, for a kind of sad 20.19 mpg average. According to the EPA, the combined score for my car was supposed to be 21 mpg, so I'm a little low. They also have the average user's mpg, which is 26.9 mpg. I'm way below that, too, which says a lot about my driving -- maybe.

They didn't rate gallons per 100 miles in 2005, so I'm on my own here. But if I take the reciprocal of my mpg (1 divided by 20.19), I get .049. Multiply that number by 100, and that's 4.9 gallons per one hundred miles (g/100m), which again isn't very great. All right, fine. Slower starts from red lights for me from now on.

Related Articles


  • Allen, Mike. "Why We Should Measure by Gallons per Mile, Not Miles per Gallon." Popular Mechanics. Oct. 1, 2009. (July 24, 2013)
  • Chang, Richard S. "The Illusion of Miles Per Gallon." The New York Times. June 20, 2008. (Aug. 9, 2013)