A rise in car "clocking" has hit unsuspecting consumers in Northern Ireland when buying second-hand motors.
Thousands of pounds are being added to the price of vehicles by dealers who reduce the number on the mileage clock, sometimes by as much as 100,000 miles.
People who buy these cars are likely to encounter problems soon after purchase, according to the Department of Enterprise, Trade and Investment's Trading Standards Service (TSS).
Often these cars are sold by dealers who pose as private sellers and not only arrange to meet buyers at roadsides or car parks, but appear at established dealerships too.
The TSS has given advice to minimise the chances of buying a clocked car including making sure second-hand buyers see all relevant paperwork and always attempting to buy from a reputable dealer.
The problem is becoming more commonplace, according to Damien Doherty, area inspector for the TSS.
"Rogue car sellers can buy the equipment to clock cars themselves for around £100," he said.
"Even though digital odometers were introduced to cut down on the number of cars being clocked, the reality is that they can be altered just as easy as the old analogue ones.
"Trading standards is becoming increasingly alarmed at the scale of the problem. Recent cases have shown the extent to which some traders will go to make profits at the expense of the ordinary, unsuspecting car buyer.
"We would like to assure the public that trading standards will take all necessary steps to identify, investigate and prosecute anyone thought to be defrauding the public."