Truck bed underside paint suggestions

[64SS350]

Hello all, I would like to ask suggestions about finishing the underside for my Suburban build. I started with black primer(hoping for highlights), then shot a light (heavy dusting) coat of grey primer to keep the color bright. Spray canned the color, no shadowing. Did I defeat the black by using the grey?

To make this more realistic, not a Pavement Princess paint job, should I use a wash of darker blue, black,?? Or a coat of dull, semi clear??

Thanks in advance, Karl 

[ctruss53]

I'm not sure I follow.

[64SS350]

Sorry... forgot the picture 

[jeffp60]

I've used diluted iron oxide craft paint, steel wool soaked in vinegar or black wash. Always over flat black paint. My under glass posts show undersides.