I have a new '14 Ecoboost, SuperCab XLT 4x4, 8ft box, with Max Tow Pkg, and the HD Pkg which has a 3.73 rear end. It has a 8200# GVWR and Cargo Capacity of 2286#. I pull a relatively small TT, which has a 4995# GVWR.
I've just finished about a 2000k mile trip towing. Went from Richmond, VA area to Blacksburg, VA, then across WV through Ohio to Michigan, back down to Columbus, OH, then to Richmond, VA and back to Blacksburg, VA.
I averaged 10.2 mpg during that time. And by making a mistake on how to return from Columbus to Richmond, I definitely put this new EcoBoost through it's paces. In Ohio, I decided to drive across WV on US 50, which is part of the "Loneliest Highway". The second half of the drive was at night, and I was going up and down 9% grades and hair pin curves. I had all the power I could ever need. There was always more power left in reserve. Coming down the mountains, most of the time the tow haul would down shift enough for engine braking. A couple of times, I just shifted to M(anual) and selected a lower gear.
I realize 5k mountains aren't 10k mountains, but 9% grades are 9% grades no matter where you are driving.
All in all, I was quite pleased.
Sunday, I left the TT in Blacksburg since we have 3 back to back games. There was no sense in pulling the trailer home, just to pull it back this coming weekend.
Filled with 87 octane pure gasoline, and driving the most gentle route home, sans trailer, I got 19.9 mpg.