Do vehicles melt? If not, why not?
and
Technically there is a way to make your self 100%protected…wear Pyrex lol XD
Weighs a ton. Breaks to easy. Can’t move faster than the Tin Man. But you aren’t going to melt 
…now where the hell did I leave my glass slippers? 
Layer a bunch of hoods. As many as you can fit on your head. Then survivor helmet on that, preferably firegear or wetsuit one.
Because acid that could melt vehicles in any sensible time would eat through flesh so fast that getting spat on by a spitter would be more of a danger than getting shot by an anti-tank rifle.