Is it possible to additive blend 2 materials

I couldn’t find a MatLayerBlend with the option to additive blend 2 materials on top of each other.
This would be really useful for creating a carpaint shader. You could have a metallic shader with a high roughness and a coating shader with a low roughness and a black diffuse so only the reflection would be added on top of the metallic shader. Or is there another way to be able to do this?