Bullet resistant covers any stupid claims against them. Never believe the words out of Musk’s mouth or his tweets.Bulletproof - there would be insane liability attached to any such claim. That will disappear from Tesla vocabulary, posthaste. Not that I have tried it, but I'm making an educated guess 1/8" of a 3 series stainless isn't going to stop much more than a 22 rimfire.
I will laugh if someone shoots their Cybertruck and punches a hole in it. (See my comment about stupid youtubers testing the glass above.)
This article claims it is 3mm thick Or about 0.120”. Very close to your 1/8” estimate.
Still beats paint On steel.No rust - salt water will definitely promote corrosion of the less expensive, readily formable 3XX alloys. Will still have to wash the vehicle from time to time in winter.