Kiwi is right, not fitted as as a prewire,

There is plenty of info on the site if you do a search, however,

Required: (prices in pounds and bits for an E46, but you get the idea)

Headunit, either 16:9 or 4:3. (£200 - £600 - ebay)
Radio Unit bm54 (NA=BM53?). (£200 - £300 - ebay)
SatNav computer either mk3 or mk4. (£150 - £400 - ebay)
Aircon relocation panel. (£30 - dealer) (you may not need this for a x5)
Satnav retrofit loom. (£120- dealer)
Gps antenna (£20 - ebay).
TV Tuner (£100-£300 - ebay)

For all this expect to pay, £800 - £1400 depending on spec and date of manufacture (newer the better/more expensive).

You don’t have to have the TV tuner, however, the TV tuner is the backup screen driver for the Monitor, so if the sat nav fails you have something on screen to fault find with.

The absolute minimum is the loom, monitor, radio, gps antenna and the SatNav computer OR the TV module.

There have been quite a few who have done a retrofit, and while its not hard, it is time consuming and requires you to be methodical.

hope this helps

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.