While it's true that you can't send your phone book to a Lexus with an iPhone, the limitation is with the car and not the phone. I have an RX400h and a Tundra with the factory bluetooth and can't sync with either but the add-on Parrot LS3200 in my Honda S2000 syncs with my iPhone every time I start the car automatically.
Actually you can argue that both the phone and the car are to blame. The Bluetooth standard uses the term "profiles" to define what BT functions a phone supports. Handsfree, Headset are the common ones for use as a phone or music headphones. When it comes to address books, there are a couple of different profiles that support different things - one profile lets you send one contact at a time (almost a file copy), and another profile supports address book access (viewing the address book on the phone). The iphone allows access to the address book, but not sending contacts. The Lexus supports Contact copy, not address book access. Additionally, the stereo music streaming BT function on the iPhone (A2DP) only supports a subset of controls - so you can send music from your iphone to BT headset or cars that support A2DP, but you can only pause and play - you can't skip to the next track.
I would like to see Apple update the BT functions on the phone, as many other phones support all these profiles. Yes, I have simplified my descriptions of things so I did skip a few steps.
BTW, if other phones can sync their address books with the Lexus, then wouldn't this make the iPhone the problem and not the car?