Out of the blue it looks like the 2.2 firmware release for the iPhone as resolved the Bluetooth connectivity problems with cars in general.

I haven’t seen any mention of this on release notes or anything, but a number of people who were struggling with the partial compatibility with their vehicles now seem to have no problem.

If you have been trying to get your phone working with your car you want to try again, delete the current pairing if you have one, and start again afresh.