I'm on 1,100 miles in a Sportline 328i. Mostly comfort and I'm averaging 20.4 mpg. My co-worker has an A5 2.0T and gets 21 mpg. I'm imagine we have pretty similar driving styles.
The A5 is 400 lbs heavier with about 30 less hp. I'm not really understanding the delta considering all engines are subject to the same laws of physics are far as I know and the N20 is a newer engine than the 2.0T FSI.