Used vehicle histories cost extra, but can be worth it if a car in question has a hidden past.

History reports can tell potential buyers whether the vehicle has been in a collision, has a lien, or if its odometer has been rolled back. They can also check whether the vehicle was stolen.

The reports are offered by CarProof, based in London, Ont., and Carfax, based in Centerville, Va. Each company offers a free version of the reports with minimal details, but gives users the option to pay approximately $50 to find out more details.

The information in the $50 reports is collected from insurance companies, dealerships, body shops and any other business where the companies can get verified records of service. Records are collected based on a Vehicle Identification Number, or VIN, which is unique to each vehicle.

"We've invested a huge amount of money into our data," CarProof Director of Product Shawn Vording told CTV Toronto's Pat Foran

To test both companies, CTV Toronto did a check on a 2007 Cadillac CTS. Carfax reported back that the car had no damage, while CarProof said it had body work done to the left front corner, at a cost of $2,458.

In response to the difference, Carfax spokesperson Chris Basso told CTV Toronto there were other examples where Carfax has uncovered damage information that CarProof was unable to locate.

"Our mission is to help Canadians make better decisions about the used cars they buy and sell," he said in a statement.

The reports are meant to gather all information on vehicles, but there is no guarantee the companies will be able to collect everything.

Both companies said that history reports should only be one step in the process of purchasing a used car. A prospective buyer should still take the vehicle for a test drive and have it checked by a mechanic.

With a report from CTV Toronto's Pat Foran