For most BMWs, you can save a TON of money if you change your own oil, brake pads, rotors, and simple problems by reading the forums. The BMW community is one of the best in this regard since there are ton of cars, many owners are enthusiasts, are on forums, and communicate/post DIYs/etc...
For my E36 M3, I saved ~$2,000 by removing my A/C controller, opening it up, and re-soldering a joint which are known to break. Just took a couple hours. Unfortunately, Just like for most current cars, i'm not sure how serviceable all of the electronic gizmos are going to be to fix in the future. However DCT is pretty reliable, but poor use of SMG can burn out clutches quickly.