During a fraud investigation, I once uncovered a car with a clean CarFax, but my inspection of the car indicated that the car was anything but clean. Title history uncovered that it was a former Alamo (owned by Enterprise) rental, and had been involved in 3 prior accidents, the last of which involved the car being rolled over onto the roof and abandoned on the beach, and then caught by the tide as it came in. Someone bought it in TX, took it to FL, fixed it, and sold it to a buy here/pay here, who in turn sold it to some poor, unsuspecting guy. Because the major rental companies are all self-insured, there is no accident history for CarFax to find. Pretty much every former rental will have a clean CarFax for that reason. That's the same reason that a totaled rental car won't have a salvage title.