There is no instant MPG option on the screen (a bummer). Instead you get a ridiculous eco-coach that displays flowers/leaves that grow based on anticipation and something else that isn't coming to mind.
The average MPGs can be reset for trip 1 or trip 2 and track the consumption for that trip (1 or 2, not litterally a single trip in the car). I left one trip (2) tracking since I got the car and reset the other (1) every time I fill up. The average displayed is actually less than what I'm getting (Titanium 4-door): 33.1 displayed, 34.2 actual. That's with 70% highway (75mph+), 30% rural/suburban (50+ w/ many stop signs). Can't complain! Previous Fusion Sport was getting 19 on a good day.
EDIT: The biggest concern isn't the mileage for me, it's the tiny gas tank. Really wish they had put at least 15 gal in this (it's listed as 12.4). Even my old 2002 Jetta had a 14.5 gal tank. Great mileage would be even better with great range...