This is my car paint node, which I have been working on for a few months now.
I believe it is nearly perfected. What makes this one special? The glitter effect. Instead of cranking up the roughness to scatter the metal flakes I scattered their reflections, allowing me to set the roughness to .01 or so. Therefore you can achieve more realistic renders because the flakes are not only randomly scattered but also reflecting more concentrated highlights, and during animations it actually sparkles. Additionally there are internal math nodes to allow easier artist control over many of the parameters including, for example, the minimum and maximum roughness sliders.
You can get many different variations by changing flake size and density. Also turning the overcoat thickness up to 1 gives a nice glossy paint material.
I am not handing this out for free.
If you wish to attain this node group you may send me a reasonable offer in a PM.
I will not be available on weekdays.
The sIBL is from HDRlabs.com
