I used to get close to that in my Burb before I lifted it, installed 35" tires and regeard to 4.10. Now it might get 12-14 on the highway.. Oddly, it almost seems to get a bit better in the city traffic, might be because I drive like a grandpa.
Not gonna get sports car feeling out of these, they're trucks. Want more power, deliver more fuel in a larger displaced engine.