Welcome to the forum. When my Jeep was stock, i would usually average 17-19mpg. I commute daily from Lowell to Boston. Reading 40 at 3/4s seems just a hair low, but the gas gage absolutely sucks. It used to say 110-115 at the half, but I could go 285-300 safely on a tank. Once the needle hits the E, you can usually get another 50 miles out of it. Since I got the lift, and didn't recalibrate the speedo, hence the odo too, I can't push it past a total of 230, which is probably more like 250-260 miles.