I did a Camaro a long time ago, guy wanted white, but not a dirty, specked looking white, but with a metallic look to it. I found a place that had reflective sign beads, the ones they put in paint on highway signs. They didn't show on the white, but reflected like metalflake when the lights hit it!
Only problem is they are sized similarly to flake, so you need a gun with a large (2.0 or bigger) cap set-up. I used my primer gun. Put the beads in a midcoat clear, sprayed over a white base, followed by lots of clear.