If you have an iPhone 3g, DON'T let iTunes upgrade it to software version 2.2.1 if you have Bluetooth in your BMW. I just found out the hard way that 2.2.1 is not compatible with BMW Bluetooth (at least in my car, a 2007 328i Coupe automatic). While Bluetooth still connects, it can't dial the phone. This is a known problem at Apple, I just got off the phone with them. There is no fix. Apple won't let you downgrade to the 2.2 software, which does work. Their only suggestion is to wait for the 3.0 software and see if that makes any difference. I'd guess that BMW will upgrade their software to work with that release at some point. In iTunes, you can disable auto-sync on the page that is displayed when you connect your iPhone to iTunes.