Mine can get better mileage than any V8, depending on how you drive it. It is more susceptible to dropping MPG depending on speed and load compared to a V8. For example, pulling my 21 foot Ranger bass boat to Mississippi and back, running 75-85, we got 12.8 mpg. My dad's 2011 3V 4.6, for example would get 16 in the same situation. Typical empty running on the interstate about 75-80 mph and I get 18-19. Following me home when I went and bought my deuce and a half, running 55 mph, the truck got 26 mpg. So speed and load really make it drop off. If you don't drive over 70, I'm sure you could get over 20 pretty easy. If you drive on back roads and run empty, you can get some really incredible mileage. If 90 percent of the time you are flying down the interstate pulling something, then you'd probably be better off getting a V8. My truck is a 2012 4dr 4wd Platinum, lifted 2". You're welcome to test drive mine if you want, GMT.
I saw 23 mpg in my wifes crew cab ecoboost one time right after we bought it according to the dashboard real time mpg thingamajig. That was on the cimmaron turnpike. Have not seen more than 21 or so since.
Pulled a 16' cargo trailer from tahlequah to ponca city and back and never got over about 8mpg, ouch!! Also took about twenty miles to finally coax it into 6th gear with the trailer on and it doesn't get much flatter than the roads south of ponca.
So yeah, you can get around twenty if you baby it, but get into the throttle a little and it drops like a rock.