Once, my mother opened the hood of her car, years ago to find a neighborhood cat curled up in one of the spaces around the engine - the cat was startled and looked up at her as if to say "AHHH! WHAT?!?"
The thing was she had opened up the hood several blocks from home in front of the local laundromat. So she drove home with this cat curled up beneath the hood.
Way back in the pre-Youtube days I found a website about a guy attaching a wireless camera to his cat so he could see what it did all day. Turns out it climbed up into the chassis of his car and hung out on the engine with two other cats.