might be an obvious one but check the service history? mine was an 02 model and when I picked it up early this year it still had what looked like a stock fuel filter - certainly not recently changed anyway, although you cant just go pulling this dudes car apart looking for faults! check around the rear wheels for rubber too :/ are the tyres new? are the panels all exactly the same colour? If not it might have been pranged. also when you test drive, get the owner to take you for a spin first, and take note of how he/she drives it. other than that mate just browse the tech forums, should give you a fair idea of what generally goes wrong with em. good luck!