My rear window was quite scratched.
After polishing it looked much better ...
... but there were still a lot of quite small scratches. Not visible when you look straight onto the window but in a certain angle it looks like the window was froozen.
I wasn't able to remove these scratches so I decided to buy a new window from Geoff (thank you very much for your help, Geoff).
The new window has the same width as my old window ...
... but is higher.
That's good because my old window was too short. It worked only because the old rubber was much bigger than the new one. With the new rubber the old window cannot be installed.
Nevertheless, the new window was a little bit to tall. After cutting 5 mm from the lower lower edge (the upper edge fitted perfectly, the lower not) it looks quite good.
Maybe I have to remove one further millimeter from the lower edge to install the piping.