Three Essex car owners who left their vehicles to warm up on their driveways returned to find they had been taken by thieves.
Police said all the cars were left with their engines running while the owners were inside their homes preparing to leave.
Officers believe the thefts in Chelmsford and Ingatestone were all planned and linked.
A spokesman said: "This isn't new, it's happened before in cold weather. Thieves notice that people turn their engines on to warm their cars up and then go inside for a cup of tea, or whatever. And then they simply get in the car and drive away."
Police said the three thefts took place between 7.20am and 7.50am on Wednesday.
A Ford Galaxy was stolen in Chelmsford and a Peugeot 407 and a Toyota Avensis were taken in Ingatestone.
Last week a £33,000 Jaguar was stolen from outside a house in Leicestershire after its owner left the engine running to de-ice the car's windscreen, police have said.
The car was stolen from outside a house in Markfield Road, Groby, at about 8.35am last Thursday as the owner waited for the car's windscreen to clear.
About 50 minutes earlier an £11,000 Ford Focus was stolen from a house in Narborough, while on Wednesday a £15,000 version of the same car was taken from outside a house on Timberwood Avenue, Groby.
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