Hi,
I have a standard 2007 Gti Edition 30 (DSG) & I always run Super Unleaded.
My commute to work is 105 Miles each way (A303 and M3:- takes around 2 hrs). If i drive like a vicar (literally) I can get 34 MPG, drive it like my hair is on fire and i get around 29 MPG. When I first got my car and tried a really frugal extra urban journey and it only returned 34 MPG. As the advertised Extra Urban MPG for this car is circa 46 MPG, I took it back to VW Dealer for them to check. They said that it was fine...... and they are all like that (what is the point of these figures when you can never get anywhere near them?!).
So my recommendation is for the sake of 5 MPG drive it like it should be driven (But stay safe).
Cheers, Andy