Toothpaste. (lots of videos on "How To" on youtube.com) Good luck! Welcome to PriusChat, BTW! (…but be careful! …it can become addictive!!!
I use the Meguiars products on Amazon.com. Believe they have a mild and a stronger version. I use the mild right now. PS- I see on Amazon it is hard to find the product. It is called Meguiars PlastX.
Note that to restore headlights properly, you should apply some clear coat after using the toothpaste method. Toothpaste has abrasives in it that basically act like a very high git sandpaper and removes the outer coat of plastic that helps keep the headlight clear. If you don't do so, the headlight will quickly fog up again. This is a good guide - you could follow it, just replace the sandpaper steps with using toothpaste. How To Restore Your Headlights Permanently With Clear Coat And Sandpaper
I was going to mention the clear-coat, but I thought it was mentioned in one of the videos! (Good point though, thanks for the reminder!)
