Dave is right, and it does vary state to state. When I've bought / sold across state lines, (done this twice) money was either owed on the car, or borrowed to buy the car, so the transactoin was supervised by a bank (to protect them, which also protects the buyer and seller!)

Also, when I bought my car in AZ, I had to title and register it there before leaving the state - it's the law. It cost me $15 is all, but again, the agent at the DMV guided us both thru the transaction and even notarized the paperwork.

A call to your DMV or secretary of state might help, Howard.