Does anyone have any experience, positive or negative, polishing scratches out of auto glass? My GTX has scratches that don't catch the fingernail, but you can feel some of them. I bought some cerium oxide powder, but before I bother finding a felt pad, etc., wonder if I'd be better off just springing for a replacement door glass. My plan was to try to polish the glass on the car, but suspect that could be quite messy. Input appreciated.

Its difficult and slow--even with the cerium oxide. You need HIGH rpms...as in die grinder--a drill ain't gonna cut it (literally)
Definately worth a try. Mask off the car (just plastic.) Don't heat up the glass too much (its possible to crack it) and work in small areas--BUT don't overwork any one area. I have an area of about 2 square inches that is optically distorted.

Don't do it.

Don't even bother.

I worked at a dealer and we had a guy who came by and repaired rock damaged glass. I asked him about removing scratchs and he said it is almost never worth it. The distorted glass is often more distracting than the scratch itself.

I've done a fair amount of glass polishing using the available kits and never had any visible distortion when polishing out really light scratches.

No high rpm's are needed (my kit specifies 1800 rpm or less), I mount the felt wheel in a small side-wheel sander. Follow the instructions and keep it wet to prevent further scratching.