Used cars that broke down almost immediately and others damaged by floods in the eastern states have fuelled a big jump in complaints in Western Australia.
Consumer claims about defective second-hand vehicles in WA have jumped by 730 per cent over the past five years to a high of 431 last year.
That compared to just 52 in 2018.
In many cases, the vehicles broke down within a few days of purchase and, in some, soon after they were driven out of the car yard.
The increase has also been attributed to sales of flood-affected vehicles and the surge in demand for used cars as COVID-19 restrictions and production shutdowns cut the supply of new cars.
"The strong demand has enticed some sellers to offload vehicles that may be defective but unsuspecting buyers may not find out until it's too late," Commissioner for Consumer Protection Trish Blake said.
"While specific warranties related to used vehicles may not apply or have expired, consumer guarantees under the Australian Consumer Law may still apply.
"So don't take 'no' for an answer when asking the seller for a refund, repair or replacement in the event of defects being discovered."
Ms Blake also urged buyers to be patient.
"Even though used vehicles are selling like hotcakes at the moment, don't be hasty and take the time to get the vehicle inspected to make sure it's mechanically sound," she said.
"Also do checks to find out more about the vehicle's history, such as if it's been written off or has money still owing on it.
"These checks are essential, especially considering that written-off vehicles from flood-affected regions in the eastern states are being sold in WA."
The commissioner cautioned those buying privately, where consumer laws don't apply.
"Buyers who choose this option need to exercise extra caution before making a purchase, as there will be no recourse available to them if something goes wrong," she said.
Among those buyers who lodged complaints last year, 427 received refunds worth $2.4 million.
Both prices and demand for used cars rose significantly during the height of the COVID-19 pandemic, as the supply of new vehicles was restricted and as more people directed discretionary spending into updating their vehicles.
Prices have dropped steadily over the past six months but remain well above pre-pandemic levels.
Demand has also declined but the market is expected to remain strong in coming years.