The bottom line
Cars aren't cheap, and a dodgy one could cost you more than money. The bottom line is that you shouldn't part with your cash unless you are satisfied that the car is "genuine" i.e. it has no hidden accident or damage history, and that it legally belongs to the person selling it to you. If, for example, the car was bought by the previous owner with a loan, it belongs to the finance company until the loan has been paid off. Ask straight questions about the car because if you are buying from a private individual, you may not have legal protection if the car subsequently proves to be faulty or the transaction was illegal.