Warming Up Your Car in Cold Weather: Experts Disagree

UPDATED 11:50 a.m. Thursday With Arctic air freezing Maryland for the first time this season, the debate renews about whether you should start your car to warm it up before you begin your daily commute. The main reason is comfort if you have to park outdoors.

Lows in the teens are forecasted for much of the area into the weekend, according to the National Weather Service. The forecast has the precipitation switching to a wintery mix or snow until early Wednesday, so commuters may have to clear off their cars before hitting the road. Lows will drop into the mid 20s Thursday and Friday nights.

If you have a remote car starter you can stay inside and sip coffee while your car warms up in the driveway. Although you need to keep an eye out; thieves will strike in the winter by stealing vehicles as they idle.

It’s a commonly-held belief that engines need to warm up before you hop in the car on days when the temperature drops below freezing. In fact, a 2009 study from Vanderbilt University found that most Americans think a car should idle for at least five minutes before its driven.

But experts now say that only applies to cars built before the 1980s that had carburetors. Since then automakers switched out carburetors for modern fuel injection systems, which regulate the ratio of air to fuel that reaches your engine. The carburetor needed warm up time in order to get the right mix of air to fuel, but fuel injection systems rely on oxygen sensors for that task.

"Idling does surprisingly little to warm the actual engine," say the folks at Popular Mechanics. "The best thing to do is start the car, take a minute to knock the ice off your windows, and get going."

SEE ALSO: Maryland Weather: Rain, Snow and Sleet in Forecast Tuesday Night

But a blogger with CarThrottle disagrees. While there's no need to let a car run in the driveway for 10 minutes — which is banned in some cities — you should give it a good 30 seconds or so to let the oil start flowing, and let the chilled metal parts in your engine warm and expand to their normal size before driving at full speed.

And the blog author warns that cold tires have less traction until they warm up, so take it easy at first. "In this cold weather, please wait till your car warms up and don’t drive like a lunatic straight out of the driveway. It will be really grateful for it," says the blogger.

Unnecessarily idling your car also affects both your health and your wallet, say those who argue against warming up a vehicle.

Health Concerns
Every 10 minutes your car runs, it releases one pound of carbon dioxide, according to the Environmental Defense Fund. This greenhouse gas is the biggest contributor to global warming.

Breathing in exhaust is also bad for your health, especially for children, the elderly and anyone with asthma. Breathing the hydrocarbons in car exhaust has been linked to increased rates of cancer, heart and lung disease, asthma and allergies, according to the EDF.

An idling car also releases carbon monoxide which can be fatal if too much of the gas is inhaled. Never let your car run in an enclosed space such as a garage.

Wasted Money

Cold weather will affect your fuel economy no matter what you do, but letting your car idle only increases the amount of gas wasted. Even with the recent plummet in gas prices, wasted gas means wasted money.

A study from Natural Resources Canada showed that idling a car for five minutes increased fuel consumption by 7 to 14 percent and a 10-minute warm-up raised that number to 12 to 19 percent.
So instead of hitting the “start engine” button before you’ve left the house, start your vehicle the old fashioned way. Your body and wallet will thank you.

Damaged Cars

Idling also causes problems with your car, once again hitting your wallet where it hurts. According to both the Hinkle Charitable Foundation and the EDF, idling for an extended period of time causes problems with the engine. The HCF says an extended idle “forces it to operate in a very inefficient and gasoline-rich mode that, over time, can degrade the engine’s performance and reduce mileage.”