The old standard wisdom is that white smooths out the angles and corners on the car and black accentuates them. The darker the color, the more pronounced that details (and paint imperfections) will be.
So if you have an incredibly angular car (like, say a Guigiaro Esprit, or the (Bertone-designed) Fiat X 1/9 of my youth) you have a choice: do you smooth it out or go to a dark color to emphasize the angularity? Metallics also soften the edges on bodywork and effectively lighten the color.
Eliges and Evoras are rounder. I have always compared the BMW Z3's appearance to a running shoe. By that analogy, an Elise is a ballet slipper. There are a lot of compound curves, though: nothing is flat on the body, and nothing is constant radius for very long. The car really does look molded rather than stamped, which, of course, the bodywork was. That makes the color choice more ambiguous - our cars share more bodywork form cues with a 427 Cobra than an Esprit.
My favorite color on the Elise is in fact Magnetic Blue. I haven't seen an Aubergine car yet, but I suspect I'd like that too. The amazing thing to me, in looking at this picture
, is that there really isn't
a bad color on the car. I'm quite happy with Saffron Yellow, but would have been just has happy with at least five other colors.
Anyway, the brightness value of those nonmetallic grays falls in the range of Laser Blue to Graphite Gray depending on shade. All of the factory reds fall in the same value range. By that reasoning, it should be quite attractive on the car.