The next time you find yourself cursing the cold while your car idles out in the driveway, ask yourself what part of your car you are warming.

If it’s a warm interior you seek, you’re on the right course.

But if you are trying to warm up the engine, you could already be heading down the road.

“Extended warm-ups are not necessary,” said John Paul, AAA Southern New England's Car Doctor. “In cold weather, allow the car to run for a minute and then drive (or) accelerate slowly until the car comes up to operating temperature.”

The operating temperature varies by vehicle and by driving conditions, but generally falls within a range of 190-250 degrees.

Modern vehicles are more intelligent than they were in the past. With massive computerization, sensors inside the car adjust the engine’s behavior based on the conditions.

In addition, idling a car for longer wastes fuel. As FuelEconomy.gov puts it, idling gets 0 miles per gallon. Cars with larger engines typically waste more gas at idle than cars with smaller engines.

Warming Up Can Break Laws

Idling also contributes to air pollution and can sometimes break the law. Denver, for instance, had a statute on the books limiting idling of vehicles to 10 minutes, but in December 2008 the City Council cut that to 5 minutes.

That was news to Sarah Hargrave, who recently moved to Denver from North Dakota, where she said everyone leaves their car running.

"You go to the grocery store, and probably half the cars in the parking lot are running while people are in getting groceries," she told KMGH-TV in Denver.

That may be so, but doing so also gives thieves an open invitation to steal your car.

"Leaving a car running on the street makes it an easy target for an opportunistic criminal who walks by and sees a running car," Milwaukee police Sgt. Mark Stanmeyer said.

Ensure Your Car Starts

But while idling your car to warm up your engine is unnecessary, there are other steps you should take to ensure your vehicle starts and runs properly on frigid mornings.

Paul said AAA Southern New England recommends motorists check to see their battery is fully charged and in proper working condition.

"At zero degrees, your car's battery can lose up to 60 percent of its power," Paul said. "Even at 32 degrees, your car's battery can be up to 35 percent weaker than at 70 degrees."

The most common sign of a weak battery is an unusual sound coming from the starter motor when the ignition key is turned, indicating difficulty in starting the engine, Paul said.

Paul also points to clean oil as especially important during the winter, when sludgy, contaminated oil can make an engine harder to turn over and start. Equally important is keeping your fuel tank at least half full in cold weather and ensuring your engine coolant is clean and at the proper level.

“Cold temperatures compound existing problems,” he said. “A car that is slow to start in 50 degree temperature may not start at all when the temperature dips below zero.”

Kick Those Tires

While most car owners pay close attention to their engines as the weather grows colder, tires may not get the same attention.

That is a mistake, according to Bill Egan, chief engineer of advanced tire technology for Goodyear Tire and Rubber Co.

Egan said a tire inflated at 32 pounds per square inch on a warm 70-degree day will register at an under inflated 26 psi in freezing weather. That not only cuts down on fuel economy, but also reduces traction on icy roads and shortens a tire’s life.

“This is not a once-a-winter check,” Egan said. “Make a point to monitor your tire pressure about twice a month in the cold months. And don't forget to check your spare.”

Proper Care Vital

Most of all, just be prepared. Even if you follow all precautions to a T, the cold weather can still leave you stuck with an uncooperative car.

“Cars and cold don’t get along,” said Jim MacPherson, a Hartford, Conn., car care expert, radio show host and author. “The plummeting temperatures cause all kinds of problems.”

The economy hasn’t helped things either. Matt Ivey, who drives a AAA tow truck to jump start stalled cars in the Boston area, said many of the automobiles he has seen this winter are in rough shape.

"Because of the economy, people don't really have enough money to repair their vehicles," he said.

But by allowing your vehicle a minute to warm up and following basic, affordable maintenance guidelines, you will give your car the best shot of making it through the winter unscathed.

“Your car will be a more dependable throughout the winter if properly cared for,” MacPherson said. “Take care of you car in the cold and it will keep you from being left out in the cold.”