Just tried my Orange SPV M3100 with my Audi A4 BT carkit, and it all appears to work fine so far.
To the Lexus guy, most in built car kits I have come accross have the ability to read the contacts off the SIM card. As this is a standard format, car manufactureres don't have to worry about accessing contacts from Symbian, Windows Mobile, Nokia etc etc etc. With my Audi, the first time it connects via Bluetooth, it reads all the contacts from the SIM card. (Note: if you already have a Bluetooth connection created, you will have to delete it and then re-create it to initiate the SIM download bit).
This maybe different on your Lexus, but the mechanism should be explained in your manuals somewhere. If not, Lexus dealers are reknowed for being very helpful, why not try them!