Used-car buyers increasingly are depending on vehicle history reports, like CarFax and AutoCheck to make sure that that the vehicle they are buying has not been crashed, stolen, flooded, etc.
Many dealerships offer free history reports to consumers, as an incentive and to persuade car buyers that they have nothing to hide. Those reports provide useful information, but it's the information that is not in the reports, or missing from the database, that should worry you.
Let's examine some of the information provided on the CarFax website about the depth and accuracy of the information they provide and sell to consumers. http://www.carfax.com/about/data_sources.cfx
CarFax touts: "The CARFAX database is the most comprehensive vehicle history database in North America, containing over 6 billion records. Records included in each CARFAX Report reveal important information about a car's history, such as an odometer reading, existence of a branded title such as a salvage/junk title, or past registration as a fleet vehicle. A CARFAX Report may not include every event in a vehicle's history, but will include the data that is reported to CARFAX for a specific vehicle identification number (VIN)."
However, CarFax also makes several discalimers:
"However, we do not have all accidents as many have never been reported, or may only have been reported to a source to which CARFAX does not have access. We recommend that any car be inspected by a qualified mechanic prior to purchase to make sure the vehicle is functioning properly and check for signs of unreported damage."
"CARFAX does not have the complete history of every vehicle. A CARFAX Vehicle History Report is based only on information supplied to CARFAX. Other information about the vehicle, including problems, may not have been reported to CARFAX. Use a Vehicle History Report as one important tool, along with a vehicle inspection and test drive, to make a better decision about a used car."
Car buyers need to be aware that a "clean" vehicle history report is not the final word on the true condition of a car. Buyers need to remain vigilant and not just "blindly" rely on the information, or lack of it, that appears in the report.
I have seen several instances where cars with "clean" vehicle history reports were being offered for sale on eBay, but which had prior damage that did not appear in the reports. See: http://mannerlaw.com/2012/04/clearwater-florida-dealer-florida-cars-sells-cars-with-clean-titles-but-buyers-need-to-look-closer/