Pretty true to that... now that I think about it my 2000 chev with 6.0, 01 Cummins 6 speed, 2012 chev 6.2 and 2014 chev with 6.2L all got 10-12 mpg no matter what I towed or where I tow. Goose neck, 4 place sled trailer, enclosed trailer, big boats. My buddy with a 2014 supercharged tundra...