It depends entirely how i drive mine, can get 38mpg out of it if drove gently on a 40 miles run, but if you drive it hard then i have seen my mfa reading as low as 22, if not lower!
But on a motorway at 55mph you can get 42 mpg, but 55 in a gti?
all in all i think mines averages round 36ish
Hope this helps!