Originally Posted by MasonCO

Every time I fill up the tank, I reset the AVG MPG and trip mileage. I have found that mine is pretty accurate on the calculation, usually withing +/- .2 MPG.

Driving speed and driving style have a lot to do with MPG. I have more of a lead foot than my wife, so if she is doing the driving, she usually is getting 5%+ better mileage than me.

We have a place in the mountains about 70 miles away. The elevation profile is in the picture below - We go up 7900 feet and down 4000 feet in elevation during the trip, for a net increase of 3900 feet. The road is a state highway, mostly 2-lanes, and the speed limit is 55 in most places. On our trips up, I usually average slightly below or right at 18MPG. By the time we do some local driving, then head back to Denver, the overall trip MPG rises to 20MPG. I am usually pushing the speed limit by 5 - 9 MPH. I am pretty sure a lift and more aggressive AT tires would drive those numbers down by 5-10%!