Listen,,, you are a cheapskate, but in all honesty I would be thinking the same way,,, unless you know a cop or someone at the DMV you could be out of luck,,, have you looked in the glove box for a manual - service records which would have the owners address or a warranty book ?,,, I sold many consignment cars years ago and we removed the books along with service records because many had the name and address.
Ask the salesman for copy service records - ask for warranty book to check some facts - ask for manual to check out some thoughts,,, you may just get lucky. now get back to work cheapskate.