Calgary police are warning of a new auto theft trend in which vehicles are stolen during test drives.

The thieves are posing as potential buyers in both dealership and private sale settings.

The crime trend was identified at the end of August, police said in a release.

Members of the Calgary Police Service's auto theft unit identified one suspect believed to be linked to 15 incidents in southern Alberta, including seven in the city.

According to the release, offenders are using a fake driver's licence to take a vehicle for a test drive, leaving the vehicle they arrived in as collateral. Once on the test drive, an accomplice shows up and drives away in the original vehicle, usually also stolen.

Last Thursday, a suspect was seen in the Red Deer area driving a Subaru Impreza that had been stolen in Calgary the previous day. Calgary officers notified the Red Deer Mounties, who arrested the suspect and three occupants without incident.

Police say a search of the vehicle turned up numerous sets of keys, stolen and fake identification documents, vehicle registration documents belonging to confirmed stolen vehicles and weapons, including a machete and a baseball bat.

Sebastian Thomas Tait, 22, of Calgary is facing 23 charges, including motor vehicle theft, identity fraud and using forged documents. He was also arrested on 10 outstanding warrants.

Police are recommending that vehicle owners making a private sale meet potential buyers in public places and ask for multiple pieces of identification. They also suggest using text messaging or phone calls instead of emails to arrange sales as these are easier to trace.