Catalytic converters are fitted to a vehicle's exhaust system to reduce the number of emissions and pollutants produced by the vehicle. They contain expensive metals that have shot up in price in recent years.
Hybrid vehicles are often targeted, as the precious metals within them are usually less corroded.
Thousands are taken every year, but data from 20 police forces in England and Wales between 2017 and 2021 indicated that only 548 suspects were charged.
The Freedom of Information (FOI) request put in by the Liberal Democrats found that 50,223 thefts were reported during the five-year period but did not include some of the country's largest police areas. The problem is likely far worse than reported, as illustrated by a second, more comprehensive FOI from OPAL and Sky News which puts the 3-year figure at almost 100,000.
London had the highest number of thefts – with 36,658. Only 544 crimes were solved.
Police across the UK have reported that they can easily be removed in under a minute and are often stolen from vehicles in car parks. They are then sold to scrapyards, online or shipped abroad.
RAC Insurance spokesperson Simon Williams said: "Catalytic converters contain a mixture of precious metals which, as this data shows, is something that criminals are increasingly exploiting.
"It's concerning to see just how unlikely it is for perpetrators to be brought to justice and reinforces why drivers need to do everything they can to avoid becoming victims in the first place.
"When at home, anyone with a lockable garage should park their car in it. But how a driver parks their car can also make a difference to how likely they are to have the catalytic converter stolen.
"The key is making it difficult for someone to get around and under a vehicle, so parking close to a wall or fence – with the exhaust nearest it – can make it harder for a car to be jacked up. In a public car park, parking alongside other vehicles is also a good idea, as is pointing the bonnet towards a wall if there is one.
"Drivers might also want to consider investing in a 'catloc' or 'cage clamp' which locks around the catalytic converter and makes it harder to remove.
"If the worst does happen, it's vital to be covered by a good and fully comprehensive insurance policy.
"Drivers can also contact their car's manufacturer to see if they offer a free catalytic converter marking service, which can help the police if they're able to recover the part."
The police haven't disclosed why so few of these crimes are resolved. However, enforcement is difficult due to the speed at which a catalytic converter can be stolen as well as a lack of traceability.
Since many catalytic converters are shipped abroad soon after the crime, tracing them and stopping the thieves is very challenging. Scrapyard regulation in these cases is also ineffective since the criminals bypass them entirely in most cases.
Police forces around the UK have launched campaigns to increase the traceability of these parts. These include adding a Smart Water solution to the vehicle or getting catalytic converters serialised to make them easier to track after a robbery.