Dude, I've been waiting for someone to bring this up. Ever since Fall has come and the lower temps my car has been an absolute... well "rocket ship." Especially in the higher rev range. The car has been downright scary from 5.5k rpm on up. And I'm as pleased as can be. The colder it gets, a new personality emerges from the engine bay. I kind of expected this with the type of intake setup we have on these cars but DAMN.
Temperature really does make a huge difference, and it's not unique to the M3. E39 M5 is an absolute snore in temps. >80-85, but in the cold a monster across the whole rev range.