I was just playing Vice City today and this happened to me. Just starting off the game, getting chased by the cops on the first mainland, and i'm in that silver DeLorean type car. I need to jump over one of the rivers (at the jump right by the nightclub) to evade the cops, so I go for it, but I figure out that I'm not going to make it once the camera pans over.
So I press the dive out button. All of a sudden I'm standing on top of the car. Over the river. So I run and jump onto land, barely making it. I turn back around, and there's the silver car, about 10 feet from the curb of the fence, over the river, suspended in air. It wasn't even close to touching the fence or anything else. It was just floating there.