We’ve syndicated this post from the Leith Cars Blog to help answer a frequently asked question.
You’ve probably noticed the long, laborious disclaimer that shows up any time someone mentions a car’s MPG. You know, the whole spiel about how these numbers are based on EPA regulated testing and actual mileage depends on your personal driving habits and you might not achieve the listed numbers in practice and so on.
That disclaimer is important, though. It’s crucial that you understand the EPA guy who tested your car was driving like your grandma, and that probably doesn’t reflect how you’re driving your car on a daily basis. This is especially true if you commute to work each morning in stop and go traffic. The sticker mileage might be beyond what you can achieve based on how you drive, but you can still track your progress and try to get better.
To do that, you’ll need to know how to calculate MPG, and that’s something we’re happy to teach you, especially because it’s super simple. The basic idea is right there in the abbreviation: miles per gallon. You’re calculating how many miles your car travels for every gallon of fuel it consumes.
The official U.S. government source for fuel economy information, fueleconomy.gov, lists two methods for calculating your MPG. The first involves using your car’s built-in odometer.
Step One: Drive to a gas station and fill your tank completely. Make a note of your car’s current overall mileage as displayed on the odometer.
Step Two: Go about your life, driving your car as you normally would. Eventually, return to the gas station and fill your tank again. Make a note of the updated reading on your odometer. Also note how many gallons it takes to fill up your tank this time.
Step Three: Subtract the first mileage number from the second one. The number you get is the total mileage you’ve traveled on this tank of gas.
Step Four: Divide the number you get from step three by the number of gallons it took to fill your tank. This is your MPG.
The second method takes advantage of a feature on modern cars called a trip odometer. It automates steps one through three of the first method by keeping track of your trip mileage separate from your vehicle’s overall miles. The next time you fill up, you can just note the required gallons and divide the reading on your trip odometer. This method only works if you remember to reset your trip odometer after every visit to the gas station.
Calculating your own MPG is a great habit to get into because you can see how fuel efficient, and therefore cost-effective, you are being. You can keep track of your MPG over time to see if you’re improving or if you’re staying the same. If you feel your numbers are a bit low, try to remember to be more patient while accelerating and more gradual while braking. There are other guides online about how to maximize your fuel efficiency, too.