Here's what I have, and the real numbers I get with the truck and towing. First long trip last fall to Yellowstone from Tampa Bay about 7500 miles.
2015 F150 XL, 2.7 EB, 2WD 3:31 axle, Super cab, Ford tow rating 7600lbs, Factory Tow package, 36g tank, Factory brake controller, Rear View Camera, Electric Axle Lock (I was lucky the dealer ordered the truck with these options), really recommend the larger tank if you can order it. I can travel when towing a good 300 plus miles a day on a tank of gas.
2015 FR Micro Lite 21DS dry wt 3900lbs Gross 4900lbs,
Andersen WD-Anti Sway hitch
Mileage just driving the truck empty always is 21-22mpg in town, highway with cruise control at 60mph have seen a little over 30mpg twice, normally very easy to get 25-28 on Hwy 75 at 65mph most trips to FT Myers etc.
Towing the 21DS out to Yellowstone the trip meter for the complete round trip was 11.3 mpg average. The mileage range is 9 to 12 mpg and if I had to pick an average from my spot check on short and longer trips I would say 10.5 to 11 mpg towing the 21DS.
The engine has plenty power at all times I could easily pass slower (coaches) etc. on the uphill grades out west towing the 21DS. On ramp acceleration to highway traffic is never a problem always feel I have enough power and speed.
Engine rpm towing at about 60mph is 1800 rpm in fifth gear will occasionally drop to 4th. I also monitor the transmission temp and only one time did it go a little over 215f for short time when going over the top of Yellowstone and then went down quickly, usually its in the 190's.
The truck with the 2.7 EB has exceeded my expectations as a daily driver and for towing my ML 21DS, hope my info helps a little bit. I call my 2.7 the little beast.