The VRayCarPaintMtl material is a material that simulates a metallic car paint. It is a complex material with four layers: a base diffuse layer, a base glossy layer, metallic flakes layer, and clear coat layer. The material allows the adjustment of each of these layers separately.
If you just want to use the metallic flakes and make your own layered materials, you can use the VRayFlakesMtl or the newer VRayStochasticFlakesMtl material.
