BMW has a specific service that they pay for (like many companies) to monitor websites. Most of the time they can farm the information from them (fan type websites) as part of some mutual agreement or obligation.
So unless you use proxy servers or mirror sites to create ghost accounts it really isn't hard to track down folks at all.
For about thirty dollars I can do the same thing with anyone here.
Everything you do on the web is traceable------everything!
2013 S4 Loaded (and NO RFT's) Awesome is an understatement
2008 MT X3
RIP you were a faithful sidekick and will be missed.
2007 AT X3 RIPOS
2000 Jeep Cherokee
1997 Twin Turbo RX-7
1984 GTI Wolfsburg Edition Neuspeed and more