If the headlight lens is just cloudy from the sun. I have used 303 Aerospace Protectant which is available at marine supply stores, unless you have a really good auto parts store. Use a cotton cloth and put some on the cloth and rub it like you were polishing metal use some force let dry and buff off with another clean cloth repeat and it should take care of about 90%. Lasts for a couple washings or rain showers. Also great on tires if you do not want a shine. Rubber molding etc. Has a good UV inhibitor in it, great stuff. Better than sanding or buffing.