I owned a car that was almost totaled in a curbside hit and run. The front driver's side axle and tire were literally folded under the driver's door.
This is not on the Carfax.
Later, the timing belt snapped and I sold it that way.
The sale is on the Carfax report, but not the timing belt replacement.
The Carfax says I took the car to the dealership for regular maintenance. I did not. I went to the fast oil change places and usually way after it was time.
The positive battery cable went bad. Instead of going to the dealer and spending $300 or more for a new cable plus labor, a local mechanic made a custom cable that was still working well when I sold it. I also replaced the camshaft position sensor myself. I ordered the part off Ebay. The Carfax report says this was done by the dealership.
My having new tires put on the car and having it smogged are the only true statements on the Carfax report.
Who reports to Carfax? Can anyone add information to a car's report? When I sold the car, I told the buyer all the above.
Buyer beware, Carfax information may be fabricated.