Quoted from Aladdin:Try the 3M Headlight Restore Kit. ...
I also had great success with the polish from 3M (3M Finish Paste Finesse it 09639). I used a rotation swinging block machine with a soft pad (lamb wool pad) (hopefully my wording is somehow ok). With this method the mylar looks afterwards like a mirror.
I found a picture to the bottle I used, but the link is in German. Maybe someone can help to find something similar at your place.
http://www.amazon.de/3M-Finish-Paste-Finesse-09639/dp/B001J4OURA