In one of my past lives I worked for an extrusion company. We used Irganox 1010 as an anti-oxidant to prevent the film that we were making from yellowing. Some type of anti-oxidant is used in the headlights but not in the cornering lights.
FYI if you want to know more or can't sleep.
http://www.polivinilplastik.com/urunler/I1010.pdf