I drove to Hay-on-wye from North Wales this weekend, no motorways just bendy hilly roads. Had 308 miles on the clock when I left, trip is about 120 miles one way. Am taking TTs advice re running in so only went up to 3.5K RPM. Averaged 42 MPG (DSG).
I'm happy with that. My GT TDI would do 62 MPG. But I didn't buy the GTI for economy.