One problem related to wiper has been reported for the 2010 BMW Z4. The most recently reported issues are listed below.
During a cold, driving rain storm, with driver & 1 passenger, started to drive. (very 1st drive in this car with cold weather) what a surprise: windshield immediately fogged up. Turned on defogger, windshield then fogged up 100% as well as all other windows - as visibility disappeared, I stopped the car & opened the windows with the blower on. No heat could be used. This process was repeated over the next 1 to 1-1/2 hours in order to continue driving. Issue was reported to BMW many times over. I had to learn that despite cold ambient temperatures w-w/o rain, snow, etc. - the a/c must be turned on in order to not fog the windows. BMW: there's nothing to fix, that's the way it is. The ambient air is directed through a portion of the engine compartment, this heats up the air. BMW stated that I may void the warranty if I modify the system to correct this problem. This has continued to occur. On a drive on CA's coast highway, with temps in the low 50's - one must still run the a/c & no heat. BMW asked: what do you have against running the a/c all the time? in addition to impaired visibility - this results in constant, very low mpg with the a/c always on. When BMW provided mpg's to fed. Agencies, I believe that BMW's a/c's were not on & these cars demand premium fuel. I spoke with a nationally known, respected tester/advisers of many vehicles - it was confirmed to me that the mpg tests are conducted without the a/c's being turned on.