I love the shape of the rear bumper on all X6M's, but since my car color is Sapphire Black, all those shapes get lost in some way, there is no contrast, that is why I painted the plastic trim that divides the upper part from the bottom part, I choose a dark gray just to make a "soft" contrast, but not sure if I went too dark, maybe the right color was more on the silver side and not titanium gray.
If someone has done this please post some pix
Check it out