York Regional Police are warning residents not to leave their vehicles running to warm them up, after a Porsche and a Mercedes were stolen from their owners' driveways this morning.

The two cars were taken from homes in the Major MacKenzie Drive and Weston Road area of Vaughan. 

Police say it's likely the work of an organized group that scopes out neighbourhoods for luxury cars left running on cold mornings, waits for the owner to go back inside, and then steals the vehicle.

"They're targeting high-end vehicles, because there's a market," said Const. Andy Pattenden. "What happens to a lot of them is that they're stolen from the driveway, quickly taken to some place where they're loaded into a shipping container, sealed up and then basically sent overseas."

Three other cars were stolen from driveways last week, bringing the total of warm-up car thefts to five this year so far.

Last year police say a total of 22 vehicles were stolen in warm-up thefts.

If you do plan to warm up your car before heading out in the morning, police say to never leave the keys inside.