Don't know how well this will work on todays windshields, but years ago, if we had an etch on our glass we would take a little toothpaste, and add a little table salt to it. Then take an old tee shirt, and put it over the end of our finger, with the mixture, and try and rub it out. Sometimes this was sucessful, and sometimes not.
As I said, I don't even know if this will work on todays glass, but you might give it a try if it looks like all other remedies have failed, and you have to replace the glass.
Remember table salt, because of it's fine grain, not Kosher salt, the grain is too big. It may take several apppliciations to do the job.
Who knows, maybe even wetting the cloth with the vinegar and water solution might help.
Just an old thought, so let us know if this tip might help. Enjoy!
