figure out your mpg?

fill you gas tank
hit tripp odometer
when you refill, devide the number of miles on the trip odometer by the number of gallons needed to re-fill the tank

OK when you dont have a working trip ODO......(dont ask)

write down miles one fill up before you start to do this
Fill tank
pay attention to the gallons you put in
look at current milage
subtract current milage from previous milage
divide by the gallons

www.gasbuddy.com Sign up for your local version (mine is www.twincitiesgasprices.com ) and use the online fuel logbook. They'll figure your mileage out for you.

<EDIT> Had to look, so here ya go.... http://www.hamiltongasprices.com/

I figured as much , I thought maybe you guys had some secret way , as you all sound pretty accurate about your mpg.I will calculate mine and see how she goes , thanks.

I was lazy and didn't read MOS'* links, but picky people say that you get best or most consistent mileage readings if you:

Fill up at the same station, same pump the second time,
Fill up at the same time of day each time,
do the three clicks "top off" method that EPA doesn't want you to do,
Make sure you calculate any variations caused by larger/smaller tire/wheel combinations, over stock.

But, you may not care for that level of accuracy, lol...

I always go to the same station. Tried a different one once in my old car and it started sputtering.