If you have a new generation BMW (anything newer than the e38/e39/e46/e52/e53 and prefacelift e83 X3) iCarly is okay...but iCarly doesn't really provide that much for the older gen BMWs. It's great on the new gen BMWs because they operate over a different communication bus system (LIN/MOST/BSD/etc).
You can search around for more details and info...but where you really see BMW owners getting their money's worth for Carly...peruse the new generation BMW forums.