The Myth of Idling Your Car Before Driving

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We’ve all heard it! And that’s why people who live in cold and snowy climates, like parts of North America — and especially those with remote starters — often fire up their engines long before they start driving. Some even start the car from the kitchen in the morning and only then start their favourite breakfast brew.

It turns out this idea of winter idling is wrong. And so are the people who believe it. A 2009 study found that on average, Canadians thought they should idle for more than five minutes before driving when temperatures were below 0 C!

Like many misconceptions, the idea behind this concept comes with a kernel of truth:

  • Cars get worse fuel economy when it is really cold out. Studies show they are at least 12 per cent less fuel-efficient.
  • It does take longer for the engine to warm up and reach an optimal driving temperature in cold weather.

According to several auto industry experts, older cars that relied on carburetors as a crucial engine component did need to warm up to work well. 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 phased out 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 running 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 during winter, you should warm the car no more than 30 seconds before you start gently driving until the thermostat is at normal. “The engine will warm up faster being driven,” Indeed it is better to turn your car off and start it again than to leave it idling.

So idling does nothing for your vehicle, but it does have several big (and avoidable) costs — wasting fuel and emitting greenhouse gas emissions and other types of pollution. To show how much fuel can be wasted, Natural Resources Canada ran an idling experiment, freezing three cars to -18 C and then driving each vehicle the same distance. Sometimes the cars were idled five minutes before driving, and sometimes 10 minutes. The result was that the more idling time, the more fuel wasted.

The test results showed that with a five-minute warm-up, total fuel consumption increased by seven to 14 per cent, and with a 10-minute warm-up, total fuel consumption increased by 12 to 19 per cent. The larger the engine, the more fuel is wasted.

Ask me about the damage to the inside of your engine that idling creates. Just because you do not see it does not mean the damage does not occur. Your engine and the environment thank you!


This is why people still think they should idle their cars in winter,” Chris Mooney, Washington Post

“If you think idling is harmless, think again,” York University

“Attention drivers! Turn off your idling engines.”

Published on December 22, 2019 under Explore, Featured by

Jerry Lupul

The Myth of Idling Your Car Before Driving


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