Originally Posted by THE TECH
In the end, there's no real way to know whether a car has been taken care of or beat on. Carfax and dealer records only tell you so much. There's no way to know if the car has been tracked its whole life or lived in a garage and never driven.
Can't you read log files off the ODB-II port? I doubt that a used car dealer would allow/help you get to that data though.