You'll get raped!
Oh wait, I did that few months ago, does it mean I got raped? Anyhow, this
might be useful. And actual details will depend on specifics: Is there a lien on the car, if so - where's the title. It might make sense to do a transaction via Ebay, so that there are some protection policies at work. Or even though you have cash - to do it through a bank.