Most eng type plastics have melt temps of 250-300 C. Arizona doesn’t get that hot.
Temperatures is enclosed spaces can indeed get up 200C when exposed to direct sunlight. If you lick your finger and then quickly touch a metal object you will get the "frying pan sizzle" and some steam. There will be no water left on the surface.
That does reach the softening point of 3D parts.
I dunno, I’ve baked cookies on the dashboard...