I own 2008 BMW 335i. The Nokia N900 syncs with my Logic 7 car audio system, however only as a bluetooth head set. Basically, this means that you can only accept, reject and end phone calls once they come in.

There is no phone book being transferred to the Logic 7 car audio.

The issue is that the N900 uses obex data exchange which is missing the PBAP bluetooth profile. PBAP is the standard for phone book synchronisation between bluetooth capable devices. Almost the entire car industry uses it including the aftermarket manufacturers with their head units.

Now, the trick is to obtain PBAP support for N900. From what I can gather, this involves recompiling the obexd with PBAP support and then pray to the gods that it won't crash.

As an example, my T-mobile G1 has full PBAP support and it works great. It even made it to the list of approved bluetooth phones by BMW.

P.S.:
The reason why this works on Ford vehicles is because Ford slept in bed with Microsoft and they have a small Windows based PC inside of the cars which supports all kinds of bluetooth profiles. Its called Sync by Microsoft and it is definitely non-standard solution.