I too saw an AstroTurf Smart car today and had the "surely that's a fire hazard" conversation with DH. I was also thinking surely it gets rusty underneath?
Years ago 3 Creme Egg cars silently drove past me - cars in the shape of Cadburys Creme eggs, about the size of a mini but totally egg shaped, painted like a creme egg - and I remember looking around to go WTF to anyone else but the place was deserted. I didn't make it up!