My wife works for Carfax. What they have depends mostly on the particular state. Different states have different requirements for what has to be reported. My wife's car had a legitimate odometer rollback (instrument cluster had to be replaced under warrenty). That didn't even show up on the report because Virginia is one of the states that records the least amount of information. I'm sure when the car is retitled it will get recorded but the dealer wasn't required to report it.

You do get to see all of a car's owners and whether it was declared a total insurance loss and salvaged. I think you can also see if the car was bought back by the dealer/maker as a lemon. This is useful information but don't expect to get detailed service records.

Let's put it this way: the vast bulk of Carfax's revenue comes from used car dealers. They don't want information that makes the car harder to sell. They want to show buyers that the car is legal but service records that detailed every little problem would only cause buyers to ask questions.

-Dylan