I see now your reason for asking. Your saying, "He doth protest to much" More then once would make me suspicious as well. If you feel the need to scan the property looking for buried cars and you have no experience, call a club and see if you can get someone to go over it with you using his equipment and know how. If the property is not yours you have to do what we do when we want to check out other peoples back yards......Ask the owners, tell them you feel a need to do it for your own peace of mind.......Gil