That’s because the game allows it,. With the trick I’ve figured out, you can tint the Matte Carbon Fiber, both Carbon Kevlar’s, Steel, Brass, Copper, Gold, and Diamond Plate.
I don’t know what “trick” he’s talking about, but you can cover each side of the car with a sticker and adjust its opacity so that the texture bleeds through while taking on some of the colour of the sticker.
The OP is correct; whatever method Turn 10 used for making the manufacturer metallic paint is unavailable to the player.
The texture for “metallic flake” isn’t even remotely similar to the texture used for the manufacturer paint. Here’s a picture of a GT86 with the original metallic white on the right and the “metallic flake” on the left:
The flakes on the right (manufacterer) are very fine; almost invisible in this lighting. By contrast, the flakes on the left (metallic flake) are very large.
“Two-tone polished” has a texture very similar—if not identical—to the manufacturer paint, but the shading is radically different.
That’s supposed to be white.
I very rarely paint my cars with anything other than manufacturer options, though, so it doesn’t affect me much.
I too have been bothered by this. The manufacturer colors are far better lookin and fibrant. Shading on the pearl is too dark and different. Metallic just isn’t the same… Hope T10 will give us a option too make are own decend metallics…