I almost view a matte paint closer to a material rather than a type of paint. I don't know the science behind it, but it seems like the material sort of swallows the light instead of reflecting it. The in-game engine is obviously responsible for mimicking light and reflection and I simply don't think the rendering engine was prepared for such a style.
One thing you could try and do your best with a matte material, and whatever else is on the car (decals, complimentary paint designs) you can try and apply some effect that gives it more of a glossy look/feel. That way you're playing with the mind with a steep contrast in glossiness. Just spit ballin'.