Too early to tell with mine since I got it with 26 miles on the clock, but economy on the road trip back from the dealer was about 27mpg, and in mixed driving since then it's been steady at 24. This is a SWB Wagon with the Ecoboost gas engine, and these numbers are from the onboard computer. Still under 1000 miles so there haven't been enough tanks through it for me to even remember to calculate by hand.
I'm hoping and expecting that my averages creeps up a bit once it's broken in. Suffice to say I'm not expecting vastly better economy than the 2.5, but happy to enjoy the added thrust and turbo sounds in the meantime...