The Body Inspection (Service) is for your 3 year corrosion warranty. You are recommended to get this done at the 1st and 3 year, then every year after that if you wish. Is it worth it? Well I would say yes if you plan to keep the car for a good length of time, if not you are paying the privilege for the next owner. Of course stone chips etc are 'self inflicted' so would go against a warranty claim. As well as checking all panels, underseal etc., they spray (waxoyl???) inside all the panels which smells for a week or two.