I get around 380-400 in my 1.8T, which includes a real mix of driving. I've seen it show over 500 miles left, but my god driving like that was boring.
I'm quite surprised that the S3s can pull off similar mileage to a tank, do they have slightly bigger tanks than the other A3s?
Id love to get that amount out of mine, even when i try not to floor it for like 2 weeks at a time, i still probably get an extra 10 miles out of my tank.