That is a low mileage car considering the age. Since the owner is your friend, you can ask him directly what issues have he encountered so far.
Explain to your friend that you just want to save a few headaches for unexpected repairs.
For example, the A/C is malfunctioning. Knowing this ahead, you are prepared for such expenses.
Perhaps posting the asking price will help so that our members here can judge if you really got a good bargain.