If you are looking for the Aux audio input, that came available some time in the 2002 model year, I think. (I can not remember the exact manufacture date.) Here are the installation instructions for cars that came equipped with the pre-wiring.

http://www.bmwmotorsports.org/pdf/BM...stallation.pdf

If you have an earlier car, you can always do the upgrade yourself. You would need to upgrade the radio module, and then the same aux kit will just connect directly to the radio in the trunk.

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SOLD
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