You can fairly easily retrofit PDC, I did it on my 2002 X5. My car has Xenon headlights and had the provision for PDC (front sensor wiring already in the car's harness). The retrofit kit (from memory) is the same whether pre or post facelift E53. Ask more, I did a write-up to have posted, but the admin hasn't yet done so.

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2002 Euro X5 (E53) 3.0 diesel (M57)
5 speed manual with UUC short shifter.
Pre-xDrive NV125 transfer case (chain & gears).
Factory Xenon headlights, Spyder LED tail lights
Updated vortex crankcase breather.
Motorsport dead pedal, factory fire extinguisher, factory first aid kit, factory F&R mud flaps, factory PDC

Bilstein B6 shocks F&R
Redline oil has replaced "lifetime" fluids (F&R diff, manual transmission, transfer case and P/S).
Dimple magnetic drain plugs in all compartments.