I am on my 4th tank now, but on my third tank of gas, I got 19 miles per gallon, up from 16 in my first two tanks. The only change I made was the decision to always drive in M-Mode, and I still took it towards my 5500 RPM limit a few times. I have already seen (I reset consumption with every tank) times early in the tank with freeway driving @ 75mph at 22+. I've actually had the opposite experience as lugnut with dash readouts using the reset consumption on fillup. In the M3, my previous Audi A4 and our Lexus GX -- they all seem to be fairly spot on.
yes, mileage Hooray! I feel vindicated as I think no one believed that I was getting >20mpg with this M3. Now, why is it that the mileage is even slightly better in "M" mode? Maybe it's the same principle as the M3 winning the mileage test against the Prius (if you haven't, you must see this on youtube) in that it's so little effort to keep the car in motion in that mode. My physics background isn't strong enough to figure it out. Anyway, the sound effects are worth it---what a great growl it has.
Just got a program on my Iphone that helps keep track of your MPG. Since taking delivery of the car in late Feb/early March 08 I have evidently been averaging 18mpg (with a high for a tank of 22 and a low of....9....)(yes, I am that guy that keeps his gas receipts for some reason - this was the first time I have every actually gone back through them though). Now that gas is fairly cheap again (under $2 for super by me in Northern NJ) my mileage has dropped as I have been having more fun. I haven't really noticed any difference w/ M mode being on or off, but that is likely due to the fact that I leave my "power" button on 95% of the time.
