I bought my 3.0si coupe at about 12,000 miles. It was a dealer service loaner, so I expected some issues. When I first drove it, I noticed a bit of a clunk shifting out of first gear. I chalked this up to either the CDV or just my driving, and soon learned to shift by holding the RPMs higher when engaging on the upshift, eliminating the clunk. It didn't bother me too much, and I wasn't in a hurry to have it looked at considering the amount of warranty remaining.
In the course of putting about 6,000 miles on the car, I experienced a few more shifting issues: a couple of times, during stop-and-go crawling in traffic jams, I had a very hard time finding first gear. I had to shift into second, maybe third, playing around with it a bit before first would finally engage. This was bothersome, as it could be a safety issue to not be able to move while traffic ahead of me is pulling away.
Then I found a problem with third gear: intermittently, and always during fast upshifts, third gear would just refuse to engage, actually grinding and knocking the shifter out of my hand in a couple of instances.
This combination of quirks led me to ask a transmission expert (shameless plug for Robert at
Gearbox Transmission in Richmond, VA) for his opinion, and he confirmed that Z4s have had third-gear issues, although this was the first time he'd heard of first-gear problems.
A few days later, armed with this information, I took the car to BMW of Fairfax and described the issues. They only had the car for about 20 minutes before the service advisor came out and put me in a loaner car, saying they were opening a PUMA case and likely replacing the transmission.
This was on 8/20/09. The new transmission takes 7 business days to ship from Germany, but it should arrive on Monday 9/31 and hopefully I'll be picking the car up on Tuesday.
The moral of this story: If your Z4's manual transmission feels funny, it's not just the CDV and it's probably not you, assuming you know how to drive a manual. Take the car to the dealer ASAP, and make sure you describe EVERY symptom. There is apparently a manufacturing or design defect with certain transmissions in these cars, and BMW seems to recognize this, based on the expediency with which my issue was addressed.
DarKWing