This file includes 6 node setups for carpaint shaders. It works for blender cycles.
Also it includes a simple test scene that uses a hdri environmet, because the "blender ball" did not show all the shades. The hdri file is not included. You can download that one and others from deviantart (it is studio30.exr). Besides the hdri file I have used a meshlight lamp to test specular reflections.
*Render images included.