Consumers are being warned they risk being caught and squeezed by the tight margins plaguing the second-hand car market.
Advocates for car buyers and the industry warn Trade Me has ended the days of shopping around for big bargains.
The Herald today reveals how one car yard had a computer program designed to data-mine Trade Me for other bidders' details. The information was used to help set prices at The Auto Co and has been revealed by one of the company's sales staff.
Panel beater Chris Jellie said he was blowing the whistle on some practices in the car importation industry which were putting consumers at a disadvantage.
While prices have become more standard, car dealers are finding other ways to make profit. They are also being squeezed by deregulation which has made it easier to become a registered car dealer and removed requirements to have a permanent base.