I wouldn't say they aren't visible during the day. The are not as obvious as the OEM just because of the colour themselves.

I took this shot this morning, but unfortunately it was a typical foggy day in San Francisco. If the weather improves in the next few days I'll post an update.

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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)