Here's a post I put on the Carrara list a while back talking about using Fake Fresnel to simulate the way some newer paints change color based on viewing angle.

Stealing heavily from Gary Beale's classic paint tutorial, but with Shader Ops Fake Fresnel added to mix colors based on viewing angle, I created a quick metallic paint shader inspired (but exaggerated to better show the effect) by the upcoming 2004 Mystichrome Cobra Mustang. A luxury I will have enjoy only as a 3D object because of how my wife so politely said I was not allowed to pillage the children's college fund to buy a new mustang, though the boy was on my side as he exclaimed "Daddy car BRRRMM!" ;)

Here is the end result

And here is the shader

Regards,
Eric Winemiller
Digital Carvers Guild
3D plug-ins for Carrara
http://digitalcarversguild.com

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins