I have the 2014 Limited w/Ecoboost and have the same thoughts/results as indicated here - 24mpg hwy at 70-75 mph on a good day. When i tried to duplicate the Consumers Reports tests of an Ex w/V6 & AWD done a 65 mph, I got 26 mpg which was the same as their tests. The problem with that is the Ex they tested is EPA rated for 23 hwy and the Ecoboost is rated at 28 mpg, which means the Ecoboost should have done BETTER than the V6 AWD (like ~5 mpg better).
I have been to 2 dealers for testing and involving Ford Customer Service. FCS was friendly, helpful and understanding, but couldn't do anything about it. Going up the ladder to Ford Consumer Affairs and then to Ford Executive Liaison Dept proved to be a total waste of time & effort. You can only communicate with them through snail-mail and all you'll get back are form letters - total screw up on Ford's part if they want to retain customers and solve problems.
There is a problem here is just like Ford screwing up the mpg testing on all of their hybrids, but Ford has addressed their lies on this one, yet.
All I can advise is to definitely take it to the dealer and involve Ford Customer Service. If enough of us do that, maybe Ford will decide to finally do something about it.