[norsairius]

To get the best calculation for what you're getting for gas mileage (I don't always rely on the computer, but it's good for a ballpark figure at least): I'd suggest going to the gas station, filling up your gas tank, and resetting the trip meter. Then go about your regular driving. Next time your car needs gas, fill up your car again, take note of the amount of gas dispensed then divide the mileage on the trip meter by the amount of gas dispensed. If you get a bad or unexpected number consistently, then you may want to get the car checked out.