This has been argued on this forum here and many others. Some of the newer cars ........I wouldn't do this on because of the plastic they are made out of. This Site Is for the e46...... Not he Prius. The windows are made of glass. If you are unsure then do a test spot on glass you don't care about. Some glass shop swear by this. It worked for me to get the scratch from my windshield.
So.......ill put it this way. If your windshield has an annoying scratch right in the middle of it. Try it. If it works awesome. If not.......well, I don't know. Ive never had it not work