For me it was to have the colour of the angel eyes and fog lights to more closely match the colour of the HID. So in short, colour.

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[B]2014 Cayenne Turbo S[B]
2007 X5 4.8 - Titanium Silver , Black Leather, Premium, Prem Sound, Sport, Rear Climate, Heated Seats, Running Boards, Lux H8, GP Thunder Fogs
2003 BMW Z4 3.0si (retired)