 I only have 30000 miles on my BMW Z4 2003; I bought it out at the end of my lease; the elec. motor for the convertible top short circuit due to run off water that enters the plastic housing where the elec. motor sits in. The water can't drain and the electric motor will rust and quit. Very expensive repair, poor design. I had the housing replaced in 2008 and now it needs to be replaced again and of course my extended warranty won't cover the repair nor will the dealership... very poor design indeed and not at all what I expected from BMW.I also just had to replace the rubber around the windshield and the cowel due to dry rot.I would have thought the convertible roof of a BMW would last