I get about 16-19 on highway and get 13.5 towing 10,000#. My dad's excursion just got 18.75 on the highway at 70mph. It is stock as far as mods go but has a 4" lift and 315"s on it. My brother gets about 17.5 -19 around town with a superchips programmer he hasn't checked it on the highway yet.