I slept one morning about 4 hours on the back seat of my '69 Camaro. I was on my way back from Navy "A" school in Illinois and dropped a fellow sailor off at his grandma's house. I had the promise of a couch, but when we got there, he said that he was afraid to scare his grandma with a stranger in the house. I understood, though I didn't like it.
FWIW, I had Gabriel HiJackers on that Camaro!