Plus having a friend allows a 2nd set of eyes to look everything over and spot things that you may miss. I have done this for several friends and stopped a buddy from buying a Mustang that had lots of rust issues and he had looked over the car many times. He was looking at all the upgrades while the guy was talking to him and pointing out stuff he wanted him to see and drawing him away from problems areas. The seller was not happy when I asked a few questions that I already knew the answer to and this caused my buddy to step back and take a better look.
