Yes, @Robin_McLaut, you will want to use both a normal map and a custom metallic map so that you can set your paint flakes to metal while the paint substrate is dielectric. If you look at some of the car paint materials that Allegorithmic has produced on Substance Source, you will see that they have quite a lot of information built into the normal map of the paint, knowing there will be a clear coat over it. To illustrate, this is one of their metallic flake materials with no clear coat, rendered large on a shader ball:
There is a lot of variation in the normal map to account for the flakes which will actually be very small so the detail does not have to be crisp. Using the same noise texture, the metallic map switches between metallic and dielectric so that the base color of the flake will be reflected in the specular reflections on each flake (giving it a metallic feel).
Your clear coat normal will smooth out the environment reflections on the surface of the material, but you want the undercoat of paint to be a bit noisy so that you reinforce the metallic flakes in the paint. Hope this helps you visualize what you need to do.