I pulled a 34 footer Forest River trailer with a 2012 F150 with the 5.0 V8 and got about 10mpg average. The rig pulled great up hills and on flats. Now I am pulling a 39 foot Jayco trailer with the 2013 F250 diesel and I get a bit better at about 12mpg towing. The F250 gets about 18mpg without towing, the F150 is about 20mpg without the tow weight. That's a 10mpg reduction on the F150 and 6mpg reduction on the F250 but to be fair the F250 is pulling 3,000lbs more weight.
No man has a good enough memory to be a successful liar. Abraham Lincoln
2016 36FBTS Pinnacle
2016 F350, 6.7, 4x4, DRW, long bed
B & W Companion 5th wheel Hitch