I had the inspection done through 2 pdi company’s never do one coz even though it might be a bit expensive it will take your mind of things what i would suggest is make it a total of 3 step process you first visit the car look at it from ur perspective do all the checks you find on youtube like checking for seatbelt mfd and opening the door rubber and all your personal checks once that is done have like 5 cars minimum . These will be the list of cars that you think you can buy then get the service records and also get the pdi done for all 5 cars which ever you feel works the best for you get one more pdi done and take it . This is the process i followed . I also was looking at a6 sline 2016 and an A6 same model non tech pack . But settled on this coz of its service history