Calgary police are teaming up with the Alberta Motor Association to try to prevent Christmas car prowlings.

Thousands of vehicles are broken into every year, and mall parking lots are a favourite target at this time of year.

Const. Tom Page calls them "crimes of opportunity."

"It takes about three seconds to pop the window ... and they generally don't enter the vehicle, they'll just reach through, grab the parcels and they are gone," he said. "So they can be smashing the window and leaving with your possessions within 10 seconds."

Police are stepping up their patrols of parking lots.

As well, motorists can get placards for their vehicles from the AMA that tells would-be thieves that all valuables have been removed.

The public is also advised to keep all purchases out of sight.