I would keep waiting...

It looks like BMW is changing its relationship with Navteq, the company that used to provide the map updates. It has been a while since Navteq published a new version. BMW dealers are saying that an update is coming soon. So, I would wait a few months to see if anythnig shows up before you spend money on a new map DVD.

As for the OS update for the nav computer itself, only a BMW dealer can update that. I would get the dealer to make sure that the latest software is fully loaded on the car before you take delivery.

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2000 E38 750iL Highline Edition, Upgraded with the lastest 2006 X5 Electronics
MKIV Navigation, 16:9 Display, Bluetooth, TV/Video with Backup Camera, Sirius, and Aux Input