Miles per tank isn't a great measurement of gas mileage ... Gas gauges, especially Ford gas gauges are extremely inaccurate.
With that said, I've averaged, per tank, as much as 46 in the past. That was when the car was still new and breaking in.
I expect to see 48 out of it this summer. Mind you, I have to take it REAL easy and drive like a grandma having a slow day ... but it's worth it when I can drive 150 miles on 3.5 gallons of gas.
2011 Focus SE 5 Speed.