Hi. I tried the SE W810i with the BMW Assist with Bluetooth System in my USA M3. It wasn't the Cingular branded version though. It didn't work correctly. Phone book paired, but subsequent updates to the handset phone book did not update the phone book in the BMW system.

The biggest problem though was that the phone audio, once a call was placed, did not route through the BMW Bluetooth system, and instead only came through the phone. If you tried to manually "transfer" the audio to the BMW system, the phone would just lock up.

After a couple of days of trying to get it to work, I sold the handset on Ebay and got a SE Z520a ... which works fine. FYI ... I also tried a SE Z525a .. .and that exhibited the same problems as the W810i ... so very odd.

Perhaps these problems have all being fixed with the Cingular version of the W810i phone ? The best thing to do is to go into a Cingular store and test the phone with your car before buying !