Our field engineers just upgraded from 2011 and 2012 F-150's to 2013 and 2014's this year, about half of the guys got Eco-Boosts (course of 27 guys, so around a dozen eco-boosts), EVERY ONE OF THEM has said they aren't getting any better mileage than their old trucks were. They're hitting 16-19mpg on highway (all we drive is highway, and we all keep track for reporting purposes). Supposedly, according to the dealerships, the Eco-boost doesn't start working for the first 20k miles (one dealership said 100k!!!! facepalm), so our guys tried to be patient with the trucks. After 50kmiles on a few of them with no improvement, we had 3 guys do warranty returns on their trucks because they thought something was wrong. 3 new Eco-boosts, same story, crappy mileage. This fleet is almost pure highway driving, most guys putting on 3000-5000 miles per month.
On the other hand, I had a 2010 Dodge Ram 4.7L that I got an honest AVERAGE 25mpg over 8mos. When I compared engine hours to miles driven during the lease, I averaged 72mph. Some tanks came out just over 28mpg. I'm the type that drives 7mph over the limit, so my interstate speeds were 77 or 82mph. Truck had ~20k on it when I picked it up, I turned in the lease at ~112k after 8months.