My 5.3 High Country gets 21-22MPG, empty, during day to day driving. Towing my Duster it gets 16-18MPG, that's not much of a hit, considering thats close to 6500lbs behind the truck. Compare that to my buddy that has a 2016 3.5EB F150 Sport Super Crew that gets similar empty MPG, he's says he gets anywhere from 20-24mpg day to day driving, but when towing his lighter Fox body to the same track at the same speed (we go together), he has only ever been able to manage 11-13MPG tops. Our other body with a 2011 Ram Sport does even better in a way. He gets about 15-17MPG towing his Valiant, and has told use he gets 19-20MPG day to day. Less MPG, but also less of a drop. The EB and all turbo engines suffer from the same problem, when the turbo spools up and forces more air in, it needs more fuel to maintain a good air/fuel ratio. The more you use the turbo, the more fuel you use. Ford can spout off all the MPG claims they want, but real life use is showing other wise.
And Ford sells 66% EB, because they push the EB more. If you read/watch the reviews, the hidden gem is almost always the 5.0 V8.