I am averaging 45 mpg in my 170. ave just clocked up 10k miles. I live in central London so all journeys start with a 30 minute "traffic heavy" portion. Really loosened up after about 6-7k miles. Just done Chippenham and back c. 200 miles and saw 49.1 overall. Granted 170 miles of that is m-way and I drive at about 75 mph. Still, I don't think that is too bad. Coming out of a 140 bhp A3 I was initially shocked at the bad economy, but now it ain't too far away. And, the extra performance more than makes up for it.