We took our 2014 F-150 in for its first oil change today, so while I was on the dealer lot I went out and looked at the 2015 Ford F-150's. The nearest equivalent to my truck with a 3.5 L Eco Boost engine and a crew cab was rated as the sticker shows above. On our way on the interstate we were pulling 24 mpg at 65 mph with the boat tail on the truck. I think 24 mpg is a good working number for highway mpg for my truck with the current aero mods.
This takes a little thinking about really. The 2015 trucks are not only 700 lbs lighter but have other fuel saving technology as well. This includes active grill shutters and start/stop technology. MY 2014 is not only 700 lbs heavier but with the aero mods it is carrying another 250 additional pounds of weight. I can do 1 mpg better on the highway. I will grant you the new 2.7 L Eco Boost rated at 26 mpg is getting better mpg but I needed a vehicle that could tow 9,000 lb 5th wheel trailer and that engine would not be able to do it. Lastly my 2014 was at least $7500 cheaper then the new equivalent truck.