I have a '05 6MT, with about 8k miles now. I do about 65% freeway and 35% city.

For the first couple of thousand miles, I was getting slightly above 20MPG. I drove like an old granny, too, since I was breaking in the car. I used Arco premium gas. From that point on until about 6k miles, I constantly got 22~22.5mpg. And a couple of times broke 23MPG.

I then switched to Shell. From 6k to 8k miles, I regularly averaged from the upper 23's (~23.7) to 25mpg all of a sudden. And I have been driving much more aggressively now. I red-line at least once a day, not because I want to, but because I absolutely have to in order to merge onto this freeway with a short on-ramp during my daily commute. But other than that, I usually shift around 2500 RPM, and occasionally shift at above 3k RPM's. And this past tank of gas, I did heel-and-toe/rev-matching every chance I could, and still got 23.7MPG.

I'm getting happier and happier about the mileage I've been getting, and honestly don't understand why some people are reporting they're only getting 17mpg when they claim they don't drive very hard. Who else is getting the same mileage that I'm getting? I can't be the only lucky one, can I?

My old Z4 3.0 (sold) used to get about 25MPG, and I probably drive the G35 coupe even harder now, and if I still get about 24MPG in the G which is heavier and has more power, that's pretty damn good!!