Overview: An average of eight million people a year buy a second-hand car. For many, it will be one of the most fraught purchases they’ll ever make. Quentin Willson continues his series of items offering help and advice to individuals who have the cash, but not the knowledge, to buy a bargain. Plus James May says happy tenth birthday to a little Japanese roadster that sparked a revival in affordable sports cars — the Mazda MX-5.