My latest tank shows 605 miles with 53 miles of gas left. AFAIK, that is the highest mileage of anyone on the fordcmaxhybridforum. It looks like I will go well over 650 miles on this tank (13 gallons). The current highest miles in one tank on the C-Max forum is 642 miles.
I had one really good trip today of 45 miles at 60.6mpg. That was averaging 30mph. Highway mileage is not the greatest, though. But, I rarely ever do any highway driving.
Matt