Just observed something odd with my fairly recently purchased 02/2007 328i last night.
I had the battery out a few days ago just to check the fluid level in the cells and confirm the condition of the "green eye" since I could not get perfectly above the battery to inspect it with it installed.
I had no apparent problems when reinstalling it, and I can't say I really noticed much of a difference in how the car starts, drives or runs (so I'm not sure that any adaptations were actually cleared by the 15 minutes without a battery installed).
Last night when merging onto the highway, I was in 3rd or 4th (6MT) around 4k accelerating at around 50% throttle and I squeezed it down to WOT. As I got close to WOT acceleration actually LESSENED and then increased again when I lifted up to 75% or so. It wasn't dramatic (a passenger wouldn't have commented) but it wasn't my imagination. It also seems that overall power output is lower than it was a week or two ago but I only noticed when calling for WOT - normal city driving was unaffected. It seems like the car was capable of being significantly faster on a country road run I did 2-3 weeks ago. The only significant change has been the battery disconnection. I did transmission and diff fluid but I don't remember if it was before or after the country run I'm thinking of, and there's no possible way that either fluid would make WOT slower than 75% throttle anyways.
No CEL, but I don't have my K+DCAN cable and DIS (or BT or AE) yet so I can't check for shadow codes.
Adaptations? Misfire (didn't feel anything)? Cosmic rays? Anyone ever heard of such a thing before? Please don't just tell me that I need a 335 to solve the acceleration problem
These are just some of the reasons I hate drive-by-wire - you have no idea what the DME is actually doing with the "throttle" and how it corresponds to where the pedal is.