What you now see is that the focus is on the 2 lights and not the whole cluster. The black shape enhances the odd shape of the light cavity. If it would be an ellipse form, a black shape would look great. Because than it looks like an eye. But the widening towards the front bumper doesn't look that well. On the smart it is part of a bigger shape, so than it's no problem.
If you want a contrasting color maybe than you can make it 2 tone and let an ellips form run sharply around the lower light. Easier said than done, I still have to make moulds for my rear lights!








