when you filled up before your trip did you top it off? or did you just go till it clicks. If you want the most accurate mpg calcutations then you should just go till it clicks everytime. Because if you just went till it clicks before the trip and then stuffed it full after the trip. then you are putting that extra half a gallon or so into your calculations and upping your MPG's
Technically, you've got it backwards. I did stop at the click on the first fill-up and then top it off on the second. This way, I figure when I say I got 22 mpg's, I did for sure. If we want to get technical, the 10.5 gallons that it took until the "click" on the second fill-up divided into the 244 miles I drove would have made it exactly 23.2 miles per gallon, but I topped it off to 11 gallons, giving me 22.1 miles per gallon. So, when I say 22 MPGs, I'm being conservative. )