I used CARFAX when looking for cars for our boys. Once we found a car that they were interested in I did a look-up on CARFAX. The first car we bought was an 86 Nissan 200SX, before looking at the car we found out it was the original owner, no issues, no wrecks and all maintenance done. The other we settled on was a 92 Honda Prelude, now this one showed the car failed emissions several times over the history of the car. With this I pulled the codes from the car to see the current issue was and it had also been in 1 minor accident. Now we went through a lot of cars before getting the Prelude and some had been in multiple accidents, some had changed hands a lot (thinking it might be a lemon). CARFAX made it a lot easier to know upfront at least some if not all of the history of the car. People do not want you to take their car to a mechanic and have it checked, but this is a great thing if you can. So CARFAX to me is my second mechanic opinion.