That melted action figure story is a good warning. I keep a cheap sunshade in the windshield now, it actually helps a lot. Takes two seconds and saves your dashboard from getting cooked.
Last summer in Phoenix, my car dashboard hit 150 degrees. I left a cheap action figure on it, and when I returned, it was a MELTED blob. That really opened my eyes to how much heat we ignore. Same thing happened to a CD case in my glovebox last year. Now I'm PARANOID about leaving any plastic in the car. It's wild what normal summer sun can do to stuff.