I got my ATS in February. The first couple of months I was averaging 20-21 mpg. This past month, the average has gone way up to 24-25 mpg.
I'm driving the same commute, which is maybe a little more city than hwy. Three factors have made a difference:
1- Weather has gotten warmer. I can definitely see an increase in mpg as the weather warmed up. (I'm in Detroit)
2- Past first oil change. I got my first oil change last month; it might be a coincidence, but I've seen a good jump since. It might be just getting more miles on the engine...
3- Smarter driving habit. I'm still driving enthusiastically here and there, but I'm taking better advantage of the manual to reduce rpm's at steady-state speeds on a regular basis.
That last point is the best part of a manual: efficiency when you want, power when you want.
Anyone else see the same?