When I bought the car, the driver's window wouldn't go up and the passenger window wouldn't go down. Apparently it's not a common problem, but it is a known problem with the Z3's. I spent $1000 having the window regulators welded back to the door and the window motors replaced. The doors had to be completely disassembled to do this, which is why it was so expensive.
The HVAC controls on most BMWs are made from biodegradable plastics, which have a half life of about 7 years according to my mechanic. I had a wreck that I believe broke the controls, but insurance denied the claim so that was another $600 to repair the knobs.
The CD player worked, but would skip when I hit a bump. I bought an aftermarket unit that works well, and added bluetooth and ipod control.
The driver's seat is starting to show signs of wear, but that's really to be expected from a ten year old car with 90000 miles. There are still no tears in the leather though.
I've had two major wrecks in this car, both of which should have totaled it, but it keeps getting fixed, and I'm fine with that because I love this car. It has kept me safe both times.
People think I'm a rich Plano brat when I drive this car, when in reality, I probably spent less on my BMW then they did on their Honda... I have driven BMW's since I was 17 except a brief hiatus where I drove an Infiniti. I won't stray again. These truly are the "Ultimate Driving Machine."
For a car that was rushed into production and had outdated parts from the beginning, it handles very well and is incredibly fast.
I plan on driving 'Lil Squeaky into the ground, but I wouldn't recommend driving in one for more than about two hours. They're not comfortable for that long. Also, the highway gas mileage isn't that much better than the city mileage; probably because it is only a 5 speed, and at highway speeds, it is revving to about 3500 RPMs.