Carfax has it good points and bad points, in my case bad points. I sold my 2007 2500HD NBS gasser with 50,000 miles, clean, 6 years old, low mileage, one owner, well maintained. The carfax came back with an accident and it does not go into detail the damage, just the fact that it was in a motor vehicle accident on a public roadway. Guy hit the rear bumper dinged the bed no structural, I lost $2500.00 when selling it. I failed to file a diminished value claim against the at fault parties insurance carrier at the time of the claim...
It may work to your advantage, in my case it did in someone else's...