I have just returned from a holiday in Austria with my A3 (and my wife). I drove across France using the A26/A4 autoroutes and through Germany using the Autobahn all the way there and a different route using some Autobahn and some ordinary roads on the way back. For return journey using the A4/A26 across France on Sunday morning I engaged the cruise control and set it to 90mph and only had to dis-engage it for the toll barriers and around Reims. The overall distance covered was 2700 miles and the overall fuel consumption was 42mpg. This included some fast driving on the Autoroutes (90mph) and Autobahns (120mph) and some much slower 'poodling' around and mountain roads in Austria. At one stage in Austria my 'fuel remaining' on the DIS showed 1090km (675 miles)! Being able to set the DIS to km and using the digital speedo in km was very useful for sticking to the 80km/hr speed limit in the tunnels in Austria. The auto-lights fuction was also very helpful as you are required by law to switch your headlights on in the tunnels. For return journey using the A4/A26 across France on Sunday morning I engaged the cruise control and set it to 90mph and only had to dis-engage it for the toll boths and around Reims. When I did a similar holiday last year in my A3 2.0TDI-140 my overall fuel consumption was 48mpg. So for 21% more power (140-170) I used 14% (42-48) more fuel. Diesel in France cost me 81p/litre, in Germany 78p/litre and in Austria 68p/litre.