This high amount of noise is a clear indication of gloss level too high. You have to lower your specular and/or glossiness. Without seeing an example of your material I cannot give you better information. If you post the screenshots for the car body material it will help. Second, from the use of Reinhard I gather that you are using the Sun. Is that correct? If so don't do it. The sun should be avoided unless you know exacly what you're doing. Cars are always phtographed with very large lights. And I mean large. A real life photo-studio for cars lifts top lights that are 40 feet long, so you need to scale your mesh light accordingly. 

Anyway, too high is  a material mistake, it's not a renderer problem. Edit your materials and you'll be fine.

Cheers.

Thanks for the tips Paolo... I had thought that all the noise was due to the fact that the render had only been baking for 10 minutes and that it would clear up on subsequent passes.