With several cold days and nights ahead, you want to make sure your car is nice and warm when you leave for work, but you might not know you're probably letting your car warm up too long. Most mechanics agree you don't have to let your car warm up for more than a couple minutes.

Marty Kroll has been working on cars more than 30 years. He says, because of computers, times have changed when it comes to warming up your car.

"As soon you start the car that computer is taking into account air temperature, engine temperature and everything. So, they really don't need to be warmed up that much," explains Kroll.

Unlike most cars made before the 1980s, cars of today also use electric fans which kick in based on your engine's temperature.

"The computer will turn the fan on, the cooling fan, when it needs to be turned on," adds 

Hopefully, your defrosters work well. As long as you can see out your windshields you can be off in a flash.

"Probably two minutes," says Kroll.

Idling wastes time. It has other downsides, too. You could end up throwing money out the window on extra gas and repairs.

"Yeah, you're wasting gas. It's not necessary," says Kroll. "Over the long run the argument could be made that idling time is harder on the engine than cruising down the road."

Kroll says the "two minute guideline" also applies to most trucks, vans, and diesel engines.

READ MORE | AAA Automobile care and maintenance tips