One of the posts I made a while back I still get lots of questions about and that is in relation to Bluetooth Car Kit support of Windows Mobile. (http://blogs.msdn.com/jasonlan/archive/2005/11/23/496368.aspx)

The challenge is that differing car kits have implemented differing variants of the Bluetooth standard and profiles making it really confusing as to whether a phone will actually work with your car.

I have a BMW and even BMW's support of Mobile Phone's and Bluetooth is pretty limited http://www.bmw.co.uk/bluetooth/

Very few actually support full capability!

I just discovered this very handy utility which extends Bluetooth Car Kit support for Audi, Parrot, BMW and others....  http://www.jetwaremobile.com/bthfx/support.htm

It's been tested on a whole series of Windows Mobile devices such as:

HTC "Typhoon" SmartPhones 
   Audiovox SMT5600

   iMate SP3

   Dopod xxxxx

Motorola MPX220

HTC "Wizard" Pocket PC phones

   iMate K-Jam

   Cingular 8125

HTC "Tornado" SmartPhones

HTC "Faraday" SmartPhones

Cingular 2125

HTC "Universal"

Treo 700w (does not support voice dialing or in-band ringtones)

The best feature I really like is it's ability to choose which contacts to sync.  My BMW I-drive has a limit to the number of contacts it will sync and it does it in alphabetical order so I rarely get (m)any of my contacts on the car phonebook :(

This solution allows you to choose by category which contacts to sync :)