The BMT BT systems both work equally well with or without navigation. Do a search on this forum... I wrote up a comparison of the Parrot system versus the BMW system. The Parrot is great for other cars, but the BMW system is superior. I have a Honda Odyssey, and I am planning to install a Parrot in it. But, for the BMW, the BMW BT system is the easy choice.

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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