When I worked at the Buick Dealer we had a Riviera with GM's "Firethorn" metallic. After sending it to the body shop for some touch up, they couldn't match it even with blending. Long story short, we got the factory rep involved and he got Fisher Body reps and finally Dupont themselves. They finally figured out what the issue was. Looking through a magnifier, you could clearly see the metallic was standing on end when it dried. There was a half dozen cars on the paint line that they didn't turn the "Electrostatic" machine off and all the metallic was standing on end. It was a beautiful paint job but impossible to duplicate or match. GM paid to repaint the whole thing.
Steely Dan Can't Buy a Thrill Side B 
