Pure highway empty I can get between 14 and 15. When I travel to NM, CO etc it does a little better.
What speed are you driving on the highway? Our Interstate speed limit is 75, and 80 in both MT and SD. I typically just set the cruise 3-5 over. IIRC at least one section of TX Interstate is 85MPH speed limit. If I could have a 7.3L gas 3/4 ton crew running empty @ 80MPH getting 14-15 I'd be as pleased as can be. I'm suspecting 11ish MPG @ that speed is probably a more reasonable expectation.
