Our Skoda was attacked by a rubbish collection lorry and the front passenger window looked so horrendous that my son was almost in tears because he was in possession of the car at the time. However I set to work with wire wool , cutting polish, toothpaste and t-cut. It all came out . Then I dropped the wire wool, picked it up, gave the last bit a little rub and made it ten times worse as there must have been grit in the wool! In the end after another hour or so of work it has just about disappeared but I was so cross with myself.