- 1). Fill up your tank at a gas station and write down the mileage that the odometer says before you leave. An example would be your odometer says 31,000 miles. Make sure to fill the tank, not just get some gas. Place the paper in the glove compartment or a safe place where you will know where it is when you need it next.
- 2). Drive the vehicle until you need to put more gas in it. It doesn't have to be empty, but you will want to put some mileage on it to get a good average.
- 3). Fill the tank up again and write down how many gallons it took to fill it up. Let's say you need 10 gallons of gas to completely fill the tank.
- 4). Write down the new mileage on your paper. Subtract the first mileage (from Step1) from the new mileage and write down the answer. Your new mileage is 31, 200. Take the new mileage reading of 31,200 and subtract the first mileage reading of 31,000. You are left with 200 miles.
- 5). Divide the number of miles you drove by the number of gallons of gas it took to fill the tank. The answer will be your miles per gallon. Divide the 200 miles you drove by the 10 gallons of gas you used; 200 divided by 10 equals 20. You are getting 20 miles to the gallon in our example.
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