Here's my results up to now on my gas door. Most of the defects came out. I had to use polishing compound (worked by hand to be safe) followed by Meguair's No. 9 and you can still see the scratch in the lights reflection. In person you can only see it with the light just right but my point is, it is really difficult for a weekend warrior to get 2 or 3 scratches out, not to mention a whole car of them. I spent 1/2 hour for a 5 x 5 piece of metal and it's still not perfect.

Sorry for the hijack but I want you to understand why so many are recommending a real pro.
Follow Mike's advise even if you think it costs way too much. (except the part about the previous owner)