This is so simple it may make you want to shake your head, don't though. We need you to shake a spray can.
Step 1: Item Needed.
Go to a big box store and get
- Rustoleum 2X gloss clear
- pay about $4
- be over 18 years old
Step 2: Clean Your Headlights.
I'll let you figure out which method to try (see INTERNET). After you are happy with the cleanliness of the plastic. Apply the clear spay paint.
This spray paint doesn't yellow in sunlight. It also bonds to plastic. I believe that it fills in the minute pits in the plastic.
You can mask off if you like. I didn't since it was clear anyways. This will dry to touch in a few minutes. ( if it isn't raining I suppose)
In this pic you can see the dramatic difference.