Kaitlin Evans parked her car in a commuter car park in Brisbane's south-east one morning in January and went to work.
When she returned to her car that afternoon and turned on the ignition, the engine roared so loudly that she thought the sound was coming from another vehicle.
"I turned my car off and then I turned it on again," Ms Evans said.
"It was still really loud."
Someone had stolen her catalytic converter.
Most victims are clueless about the crime and only find out that their converters are missing once their car is inspected by a mechanic.
Ms Evans, who works in a call centre, only knew about the crime because a colleague had previously had a converter stolen.
She said she could hear other vehicles in the car park were rumbling like hers when she checked underneath her car.
"It turned out there was four of us in that one car park that day that had our catalytic converters taken from under our cars," she said.
Thieves steal catalytic converters, or "cats", as they contain platinum, palladium and rhodium — precious metals that are more valuable than gold.
The converters – which reduce harmful emissions in petrol cars — can be cut from the underbody in minutes and sold on the black market to scrap metal recyclers for a couple of hundred dollars.
They are then shipped to refineries overseas where the metals are extracted.
The price of palladium is currently $US1,380 an ounce, while rhodium is roughly three times the price of gold at $US6,500 an ounce.
The high market price of the metals has led to an increase in catalytic converter thefts in recent years.
Motor Trades Association of Queensland chief executive Rod Camm said it was a huge issue in the US.
"But recently, certainly this year has been exploding, and that's the only word for it, in Australia," he said.
Gold Coast mechanic Alan Mcguirty said people were stealing the converters for quick cash and blamed the cost of living for the spike in thefts.
He said it cost victims thousands of dollars, with some forced to wait several weeks for their cars to be repaired due to a shortage of car parts.
"Customers are getting upset because they're without their vehicles," he said.
"They're having to park them up, or they have to hire vehicles — it's an inconvenience for everybody."
Thieves typically target car yards, shopping centres and car parks as they can swipe several converters from parked vehicles within an hour.
Sydney mechanic Omar El-Dadoun said he once served a customer who had converters stolen from three cars which were parked in his backyard.
"No remorse these blokes, honestly," Mr El-Dadoun said.
The rise in catalytic converter thefts has prompted police to take a proactive stance on the issue.
Queensland police set up a small strike force in February in response to a marked increase in thefts across the south-east region.
Queensland police officer Geoff Sheldon said there were a lot of thefts on the Gold Coast.
"But they're also up in the Ipswich area and South Brisbane and Logan," Superintendent Sheldon said.
He said three people, including a 16-year-old boy, were arrested and charged with multiple stealing offences and trespass as a result of the two-month-operation.
A NSW Police spokesperson said officers began recording the theft of catalytic converters as a standalone project in August 2021 "to properly quantify and clarify the thefts of this type of vehicle part".
Figures from the NSW Bureau of Crime Statistics and Research show there were 194 catalytic converter thefts recorded across the state in 2022.
A catalytic converter recycler, who did not want to be named, told the ABC the black market was destroying the industry, and that the police sometimes targeted legitimate businesses who purchased parts that were legally obtained.
"It's the guys that aren't doing paperwork and aren't paying GST," the buyer said.
"They're making it so difficult for us."
The buyer said there was "a certain section of society" that would do anything for a dollar.
"These are the same people stealing cars, they will break into your house and take a TV, and they will cut the 'cat' off your vehicle," the buyer said.
"We don't deal with them, but there are plenty out there."
Automotive industry groups are calling for harsher penalties and improved devices to deter thieves.
Design flaw
Mr Camm said some vehicle manufacturers had made catalytic converters "a bit too accessible".
"But the parts, there's no serial number, there's no distinct marking on them," Mr Camm said.
"There's paint you can put on them, but the problem is you can't just put random paint on the converters because they get very hot.
"So certainly, we are exploring with manufacturers the prospect of being able to mark these, obviously a serial number would be best, but that process takes time."
A spokesperson for Toyota, which produces high-clearance vehicles that tend to be targeted, said the company was aware of the criminal activity and would "work with the authorities to provide any information that is needed".
