My car is 11. However, unless I had to I wouldn't buy an 8 or 9 year old car. I bought mine when it was approaching it's 5th birthday (like a family member so it is!). I bought this from a BMW main dealer who gave me a comprehensive warranty. The car is a high spec and it had one owner and less than 50k miles on the clock. I paid with cash and have had free motoring since (apart from servicing and minor repairs (about 1,000 euro). Oh, and I own the car too!
Off topic from the PCP thread but @Firefly have you had any bother getting insurance for a car of that age? My car is almost 10 years old and running perfectly. My one concern is that getting insurance may be more difficult as the car ages. Have you found this to be the case?