I have been kicking around ideas for my white one too. I have black wheels,on my black X5 but I am not really feeling it for the white one
I think I might do gun metal or I even started thinking about gold or bronze those seem to work wellon white and it's less common and would really set it apart from the masses.
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X5M, Eisenmann exhaust, 22" HRE wheels, catless down pipes, Stage II tune/X5 Diesel, Lowered & Tuned