I run a 2005 Porsche Cayenne V6 with 45k miles on it. The car is now outside manufacturer's warranty. Since buying the car in 2006, we have always serviced the car at Porsche main dealers and received some fairly horrendous sized bills for standard servicing. I have always been under, the probably incorrect apprehension that only main dealers will have the diagnostic software that will allow the car to properly serviced and repaired. As the used car value of the car is now so low, we have taken the view that we might as well 'run the car into the ground'. Could you therefore please advise on a garage network that you would recommend to service the car? Also any help on extended warranties would be appreciated.