Many headlights now have plastic headlights instead of glass, and the plastic is susceptible to discoloration and weathering, which affects how much light gets through.
Headlight cleaners promise to fix that. Consumer Reports tested cleaners from 3M, Sylvania, Turtle Wax, and Fast Brite, an infomercial product.
Using a headlight cleaner takes a lot more work than just wiping on a cleaner and then wiping it off. To start, you want to mask off the area around the headlights. Next you need to remove any remaining coating or oxidized plastic on the lenses. Depending on the product, that might involve sanding -- either by hand or with a drill. You might even need to do some polishing and more sanding. And with some of the products, you'll need to apply a final sealant or top coat.
Testers measure the headlights' brightness before using each cleaner and afterward. The brightness often doubled.
But there were trade-offs with some of the cleaners. The $17 Fast Brite was the easiest and fastest to use, but it left headlights noticeably less clear and its sealant wore off.
The Turtle Wax's Headlight Restorer left headlights clearer, but its sealant also wore off.
The best overall cleaner? The Headlight Restoration Kit from Sylvania. It works well on all types of headlight lenses.
But a caution from Consumer Reports -- headlight cleaners are abrasive and can damage lenses. First, try using a glass cleaner—that may be all you need. But if that doesn't work, then it's time to consider a headlight cleaner.