Is there Any Need to Idle your Car Before Driving in the Winter?

From the Washington Post:

We’ve all heard the idea: In winter, your car needs a little time to warm up before you can drive it. And that’s why across the United States, people who live in cold and snowy places — and especially those whose cars have remote starters — often fire up their engines long before they start driving. Heck, they might even start the car from the kitchen in the morning, and only then start the coffee brewing.

But it turns out that this idea of idling your car during the winter is just wrong. And so are the many, many Americans who believe it — one 2009 study found that on average, Americans thought they should idle for over 5 minutes before driving when temperatures were below 32 degrees! 

Like many misconceptions, the idea behind winter car idling begins with a kernel of truth. Cars do get worse fuel economy when it’s really cold out — they are at least 12 percent less fuel efficient, according to Environmental Protection Agency and Energy Department. And it does take longer for the engine to warm up and reach an optimal driving temperature in cold weather.

Moreover, older cars — which relied on carburetors as a crucial engine component  — did need to warm up to work well, according to several auto industry experts. Without warming up, the carburetor would not necessarily be able to get the right mix of air and fuel in the engine — and the car might stall out. During the 1980s and into the early 1990s, however, the auto industry did away with carburetors in favor of electronic fuel injection, which uses sensors to supply fuel to the engine and get the right air and fuel mix.This makes the problem of warming up the car before driving irrelevant, because the sensors monitor and adjust to temperature conditions.

Idling in winter thus has no benefit to your (presumably modern) car. Auto experts today say that you should warm up the car no more than 30 seconds before you start driving in winter. “The engine will warm up faster being driven,” the EPA and DOE explain. Indeed, it is better to turn your engine off and start it again than to leave it idling. (As many readers pointed out after this post was first published, it’s always important to be careful driving in winter, and clear your windshield of any ice.). See the full Washington Post article, here.

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