Not sure if the markings are etched, or laser'd in to the glass. If etched, have you looked at the hobby store for a glass-etching kit? Though, I'm not so sure you could "remove" the markings and return the glass to a glazed finish. But, if you are creative, you might be able to to think of a way to... "re-etch" something else over the current markings. You know.. kind of like people do with old tattoos and want a different picture... hahahaha. The current etching isn't that big. Perhaps a solid block etched over it, and turned in to an "XV" or something?
Any idea if there is some sort of safety, regulation or insurance-reason the etching is "required" on there? If not, and you do this.. maybe you come up with a whole new way to start customizing car windows (just imagine little etched borders around them all). Hahahaa.