I've downloaded some car models, and after applying the scale on them, it became apparent that some of them have a narrower fresnel angle, so only the clearcoat is visible on most of the object.
I've made up a simplified .blend file, which i've uploaded here.
the two objects have the same topology, and are joined and using the same material slot, but the left uses faces pulled from the car model, and the right uses freshly added faces.
It's also not affected by texture space, UV Mapping, or face orientation.
any advice would be greatly appreciated.