Just had a chat with my colleague over in Hamburg, Germany. He recently took delivery of his 5 door DSG equipped GTD, and last weekend, he went with his family from Buchen (near Hamburg) to Nuremberg a distance of approx 650km (400 miles), so an 800 mile round trip with a new car (has approx 2,100km on it so far).
According to him, travelling at approx 130km/hr (80mph) on the autobahn's (as he had his small child in the car), with cruise set for a good deal of the journey, for the overall trip he averaged 4.2 l/km which equates to approx 67mpg. Assuming approx 5-10% inaccuracy for the trip computer, it would translate to 60-64mpg true.
Not too shabby for a fully loaded car with DSG and 184hp. I'd be well happy with that and should even improve very slightly as the miles pile on. Oh, and by the way, he said for cruising on the motorway, he's never been in a car so well suited. Quiet, supple, comfortable and with plenty of poke when the need arises. He loves his GTD (and he had a BMW 320d before).