I regularly get near 20mpg on the highway....but that is at 65 or so, on summer tires (not off-road knobbies oreven all seasons) and I live in Florida where it's very flat and almost always glassy smooth.
That said: 19 turns into 13 very easily if you get too happy with the loud pedal.
When a four year old starts making my payments....THEN the little snot slinger gets a say in what he rides in
"Now climb back there and shut up, before you ride in the spare tire compartment"......"whiner"