My built-in car phone is kind of obsolete. I was wondering what would it take to upgrade it to a bluetooth system. Would the existing wiring need to be removed? How difficult would it be to perform this installation? Any help would be greatly appreciated....Thanks in advance.

Have you searched the forums for the words bluetooth upgrade? Try that imo.

Some have installed the Parrot system. It's the cheapest route but for the most OEM install look go to bimmernav.com. Martin from bimmernav is a frequent visitor and sponsor here.
Depends what phone you have or which one you want to buy to get the cradle. But the voice recognition will work for phone and nav with out having the phone in a cradle. If you don't want the phone in the arm rest, there is a basic tray option to fill the missing phone spot just like the trays under the arm pad now.
They don't specifically make a cradle for the Razr for the e38, but a little work with a dremel and the one for an x5 will fit.

Thanks for the quick reply DanBergundy and RIboater.

DanBergundy: I did search but couldn't find any pertinent information about upgrading from the CMT5000VR. I wanted to be sure that there was no need to install new wiring from the armrest to the trunk.

RIboater: I have an iPhone and a treo 680 so I'm leaning towards the bluetooth option without a cradle and installing the tray you speak of. I will check out bimmernav.

This will be one thing on my list of potential upgrades. Hopefully, I'll put MKIV and the 16:9 first, then the bluetooth and whatnot, depending on the funds.

I"m thinking about that new iphone because it's "cool" and my ipod has died and it has itunes in it. The down side is I'd have to give up my docking cradle I have for my razr since they don't make one for the iphone. That means giving up charging of the phone and use of the roof mount antenna which the cradle gives you both.