In the chilly winter weather many drivers think warming up their car by leaving the engine idling makes smart sense. Actually, it can be dangerous in a number of ways.

First, leaving an unoccupied vehicle running invites theft. A local Indiana news report recently focused on a spike in car thefts due to people warming up their cars and leaving the keys inside. Nationally, more than 57,000 vehicles were reported stolen when a key or keyless device was left inside the unoccupied vehicle, according to the National Insurance Crime Bureau.

Leaving a car idling can cause engine problems, too. Idling time leads to raw gasoline seeping into the oil, breaking down the oil's lubrication properties and increasing wear on the engine. Idling can strip away some of the oil from components causing engine problems down the line.

Thirdly, leaving an unoccupied vehicle running — even when it is in park — is never entirely safe. It causes excessive fumes in the area where it is parked. Moreover, motor vehicle systems do fail from time to time, and if the car should unexpectedly move or roll with no driver at the wheel, it could lead to a collision with another vehicle or a pedestrian.