A stolen National Crime Agency BMW has been recovered after thieves used it to flag down a female motorist.
At least one vehicle was stopped by men posing as police officers after the car was stolen from an address in Solihull on Saturday.
West Midlands Police said a woman reported two men using the unmarked law enforcement car after being asked to get into the vehicle, which is fitted with blue lights.
The silver BMW 1 Series was later recovered undamaged in Kings Heath, the force said.
It is believed to have been taken in a burglary but had not been deliberately targeted.
Detective Chief Inspector Craig Underwood, from Solihull Police, said: "A police officer will always show their warrant card as proof of their identity. If this is not shown or you have any concerns then please call us on 101."
No arrests have been made.