Maybe you have never bothered, but to me headlight lenses which are foggy, cloudy, and just unsightly are a pain. And that's setting aside the fact they hinder your headlights from being as bright as they could be, should be, during nighttime driving.
I have a couple of older cars and I can't tell you how many times I have gone into the auto store or the auto detailing section of a store to find a solution. I stare and stare. I pick up boxes, read labels, look online while browsing for the best product.
Do any of them really, really work?
I really cannot answer that specific question, but I can show you a sequence which worked really, really well.
This appears to be one of those tasks in which you have go for it or just don't do anything because it takes several steps. But as you will see...the payoff is well worth it. My guess is that despite the title of the video it will take you longer than five-minutes per headlight lens. However, it still think it's important to show it is possible.
Pay close attention to the steps...cleaning, then severe abbrasives (aluminum foil?), becoming less and less so until you get to a clean layer of plastic or acrylic on the lens, then polishing.