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Step 1
Fill your gas tank. To determine gas mileage, it is important that your tank be on full before you begin. Although some attempt to determine gas mileage by filling with a specific number of gallons once the vehicle is empty and noting the miles traveled when the vehicle is on empty again, this can be deceiving. It is difficult to tell how much gas is actually in the tank when it registers empty. A difference of one gallon can throw the calculations off.
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Step 2
Write down the mileage on the odometer or reset the mileage counter located near the odometer. Drive your vehicle as usual until ready to refuel, Keep in mind that mileage varies according to the driving conditions. Driving a long stretch on a highway will result in better gas mileage that city driving.
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Step 3
Write down the ending mileage before you refuel. Fill the tank and write down the number of gallons it required to fill the tank.
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Step 4
Divide the number of miles driven by the number of gallons used to find the gas mileage for your vehicle. If you drove 200 miles and used 6 gallons, your gas mileage is 33.3 miles per gallon.














