Transportation: Should I Warm Up My Car on a Cold Day?

It’s the age-old dilemma—to warm or not to warm.  Okay, maybe it’s not THAT big a dilemma, but it’s still an important question. There are some people who wouldn’t dream of wasting a drop of gas even at ten below zero to let their engine idle, while others couldn’t imagine stepping into a freezing car interior without letting the engine run for 15 minutes or more. You may be somewhere in the middle on this issue. Or you may be feeling guilty if you do let your car warm up. So the real question is: are you harming the environment by doing so?

Unfortunately, the answer isn’t completely simple; there’s no yes or no response. Some say that warming is the only way to get the fluids in the car flowing. Others say that’s nonsense with today’s modern cars.  In 2009, General Motors sent out a recommendation to all drivers. They advised that warming up a car will help it to emit fewer hydrocarbons during the first few minutes of driving. The car maker claims that the engine must be warm in order to trap those unburned hydrocarbons. This information came on the heels of the release of their new car starters, so take it for what it’s worth.

If you’re in the camp that just trudges out there and scrapes the windows cold, you’ve got a good argument too. The Environmental Protection Agency claims that today’s cars don’t need long warm ups even in the coldest weather. In fact, they say that if you do let your car idle for a long time, you may be causing unnecessary wear to your engine.

AAA, the roadside assistance gurus, say that you can sense when a car is ready to hit the road in cold weather. They recommend giving the car a few minutes to get itself together before pumping on the gas pedal. Doing so will prolong the life of your car.

Many cities have started cracking down on idlers because officials see it as an invitation to automobile thieves. In some cities, there’s a full ban on letting your car idle while you’re inside the house. Other cities set a time limit on how long a vehicle can run with no one in it.

So what’s the middle ground? Experts suggest driving out of your driveway slowly and proceeding at a slow speed for the first minute or two. Modern cars have the advantage of electric fuel systems and can take the bitter cold better than cars of the past.

Of course, there are some good reasons for starting your car and going back in for a second cup of coffee. If you have small children or an infant, you definitely don’t want to expose them to a frigid interior. If it’s below zero or close to it, let the car run with the heat on for a few minutes. If you’re traveling with a pet, do the same. Consider that pets, children, the elderly, and the ill are especially sensitive to cold, so if you’ve got a passenger who falls into one of these categories, err on the side of warmth.

Another reason you may want to idle is so that your windows and mirrors have a chance to melt and defrost. Many a harried driver who is late for work has caused an accident by driving with only a partially scraped windshield. It takes time for an entire windshield to be warm enough to scrape, and most people are too impatient to invest the time. If you find that you have little tolerance for standing around while the ice melts, turn your car on and then finish dressing. You may waste a little gas, but you may save a life—yours or someone else’s.

What about if you’re driving a hybrid? How long will it take to heat up? Ford claims that hybrid engines warm up in just about the same time any other car’s engine would, so no special treatment is required.

Weigh the benefits of letting your car idle while it warms up. Few people in a room can agree on the whether it’s a good idea or not and everyone is happy to offer their opinion. It’s really about your lifestyle. If you have to get the kids to preschool in freezing temperatures, let the car warm up even if it means you’ll be a few minutes late. It will give you chance to dress everyone warmly and scrape the windows. You might consider getting up ten minutes earlier in the winter months to allow time to scrape your windows whether you idle the car or not.

It comes down to safety—that of the passengers, yourself and other drivers on the road. If you can’t see because you haven’t scraped, you’re a liability on the road. If you want to stay green, invest in a windshield cover that helps melt the snow or a heated ice scraper that allows you to get on the road faster if you haven’t warmed up