Here is the way I do it. Fill your gas tank all the way. Reset your trip odometer or write down the mileage number from the odometer. The next time you get gas, fill your tank all the way then write down the amount of gallons you put in the tank. Then write down the mileage number from your trip odometer. If you don't have a trip odometer, write down the mileage form the odometer and subtract the number from the last time you filled up. Now you have the amount of gallons you used and the amount of miles driven. Now divide the amount of gallons you just purchased by the number of miles driven. There you have it. For example, say you just put in 12.6 gallons and you drove 330 miles, then divide 330 by 12.6, that would be 26 miles to the gallon. Thanks, Mike
