I get about 440 miles from my tank, it's all relative to your commute length and how you drive the car, so hard to say how good or bad that is, although whatever you're doing, you're on the good end unless you're having to drive like a nun on long journeys to achieve it.
If I was paying a visit to relatives in Southampton, from Newcastle and maintaining 75-80mph on the motorways and dual carriageways, I’d probably be doing a true 55mpg (570 miles from full to “zero” in the MFD), as it is around the doors with a heavy right foot and a 12 mile each way commute, I do about 44mpg (450 miles). For you to get 515 miles from your full tank, I doubt you’ve been short changed by the dealership – probably been filled to first click at the pumps, which is all you should put in anyway to avoid overspill on the move.
