Just got back from a trip to Fort Davis, Texas from Central Texas. Drove, round trip, 860 miles towing my 5500# travel trailer. The fuel mileage ranged from a low of 9.0 to a high of 9.7. Most of the time I used the manual mode and the cruise control. I towed in fifth with an occasional 6th on flat ground or down hills. Up hills I shifted to 4th and on every single hill it would hold the speed with no problem. My towing speed was 60-65 mph. Overall it is a joy to drive. So stable that sometimes I forgot that the trailer was there. So much better than my 2005 Chevy 1500 CC. If the mileage gets better, that would be great. If not, then I am satisfied with what it gets now.
2012 F250 XL CC SB 4X2 w/3.73 (3800 miles)
2011 Surveyor SP275
2005 Chevy Silverado CC SB 5.3L w/3.73 (former tow vehicle)