Criminal gangs selling insurance write-offs are fuelling a surge in vehicle theft, a police force has said.
West Midlands Police said there had been a 100% increase in vehicle thefts in the force area over the past four years.
More than 10,000 cars were stolen in 2017, compared to 5,215 in 2014-15.
The force said the rise was being driven by gangs buying written-off cars from salvage auctions and then stealing cars for parts they need to fix them.
The gangs then sell on the cars for a hefty profit.
West Midlands Police Deputy Chief Constable Louisa Rolfe said: "There's a correlation between the types of cars being stolen and those available as repairable write-offs.
"It is our firm belief, supported by police intelligence, that this increase is being driven by the criminal demand for car parts."
More luxury brand cars, like Audis, BMWs and Range Rovers, are being sold at auction as repairable write-offs.
Criminals are choosing to steal cars for matching spares rather than buy expensive factory-made parts from manufacturers.
The force is calling for improved regulations of the resale of insurance write-offs and new ways to report suspicious buyer activity.
It said it would be raising its concerns with the government, the Association of British Insurers and auction and sales websites.