I got some of this for my signs I make in Papilio ink jet vinyl. They only last about a year so I got some of their clear vinyl to protect new signs I was making to replace old ones. Extends life up to 3 years, they say. I think I’ll try it on some new car windows that I leave out all the time. THey really go to pot pretty fast, even with a spray UV coating. Figured this was worth a try. I have quite a few cars/trucks still in boxes due to what the sun does to the windows in them.
http://www.papilio.com/other%20poly%20focus%20glossy%20over%20laminate.html