Dealers have been urged by information specialist HPI to access its insurance write-off database before buying a used car.
Daniel Burgess, automotive director of HPI, warned that failure to do so could result in "an even greater risk of potentially buying a death trap.
Any vehicle that has been declared a write-off by an insurance company (i.e. the company refuses to insure it) is placed into an industry-recognised damage classification, depending on its condition.
The classifications range from category A (the decision that a car is fit for scrap only and it should never reappear on the road) to category D (vehicle is damaged and insurer has decided not to repair).
Daniel Burgess said: "Dealers need to be aware that even category C or D write-offs can have a big impact on the value of a vehicle. A car worth £5000 could lose up to 20 per cent of its value if it has been declared a category D write-off at any stage.
"An HPI Check will spot one of these cars enabling the car buyer to ensure they are getting the vehicle for the right price, or walking away from an unsafe vehicle.
Written by Terry Hazel