-This sounds like a side window, not the windshield...Is that right?
If so...
-Auto glass for windshields must be of a laminated-glass process.
-Auto glass for the side & rear windows is tempered glass
Both are "safety-glass", with different 'protection' provided from a person/animal being cut by their being broken:
-Windshield glass shards sticking to the sandwiched lamination material(s)...somewhat eliminating sharp edges.
-Tempered glass, being brittle, explodes and shatters into a zillion small oval-shaped pebbles when broken.
This eliminates the danger of sharp edges. You can still get cut, though
I'd use extra, extra caution on trying to polish tempered auto glass...especially using a buffer.
Any undo stress (going from "hot to cold" and back again, pressure, etc.)
may just be the undoing (explosion) of tempered-glass' inherent inclusions.
What I do is try to reduce imperfections by using something like Meg's #4 on a terry cloth applicator...
By Hand Only!!
After cleaning any "by-hand polishing residues"...
I'll further clean the tempered glass with a glass-cleaner like Sprayway/D120...and call it a day.
Most of these tempered glass blemishes (except perhaps some of the water-spotting)
are from the window rubbing up & down against dirty window seals. Try to keep those clean as well.
As with any procedure that you may be attempting...Please be careful.
Bob