Nokia N900 does not have Bluetooth rSAP profile which would allow connecting it to most of European carkits (VW, Skoda etc).
N900 runs linux based Maemo OS.
Project scope is to develop installable library/software that would make it possible to connect Maemo based device to car kits using rSAP profile and synchronise phonebook.
Just a note that logics from Symbian source could be used.
Symbian RSAP code is available and could be used as a startup point.
at: [url removed, login to view]
The way it works on Symbian: [url removed, login to view]
Programming code in english.
Supplied installable and source files.
Check attached architecture.