Again about the color. It's 2 materials / same paint. Not really GM's fault. If they made it metal it would not give the 5mph flex requirement.
Don't sweat it. But also don't blame them. Complex paints change when they dry and depending on the surface it can appear different. If it's that much an issue get one of the colors that does not dry as contrasting.
Remember they have to bend.. they have to shrink etc. It's not just how it looks. It's how it holds up. You want a paint that can bend when you shoot it onto a plastic component surface.