To Idle or Not to Idle in Winter Weather

How to Educate Drivers on Why “Warming Up the Car” Isn’t Necessary and May Be Illegal

Last winter’s “Arctic Blast” was one for the record books — with cities such as Chicago experiencing weeks of sub-freezing temperatures and even parts of Florida experiencing unusually cold weather. It is the kind of weather where few want to leave a warm house and head out in a cold car.

Anyone who grew up in the 1980s or earlier where cold weather was a normal part of winter probably remembers a time when dad would go out to “warm up the car.” Today, however, the mere concept of idling an engine is enough to send many into a tirade about the damage to the planet — while others may proclaim warming up could damage the engine.

The question to idle or not to idle is worthy of consideration, but the facts need to be presented.

First, dad wasn’t wrong back in the day — and we don’t mean when Fred Flintstone’s feet were the means of propulsion in a car. Rather, the idea that cars should be warmed up in cold weather just dates back to a time when carburetors were installed in nearly every car. Back then, in especially cold weather, the gasoline engines didn’t run all that well right after starting up, so “warming up” the car wasn’t just about comfort, it was about ensuring that the car would run well.

In very cold weather, it actually took a while for the engine to reach an operating temperature that matched the ability of the carburetor to mix fuel and air well enough to maximize the power output to ensure smooth operation.

“This made sense in the days where internal combustion engines had carburetors and needed to warm up to get air and fuel mixing,” explained Chriag Rathi, consulting director for Automotive Research at Frost & Sullivan.

“Over the last three decades, electronic ignition technology has made idling unnecessary because the electronic ignition does the adjustments for you based on ambient conditions,” Rathi said.

Yet, many American drivers still think they need to warm up the vehicle. It has become an accepted practice, in part because there has been little in the way of education directed at drivers. One study conducted in 2009 found most adult drivers assumed that it was necessary to warm up the car for at least five minutes before driving when the temperature was below 30 degrees.

Where the issue becomes more complex is there is some truth in the argument that engines may benefit from being warmed up — the key words being “some” and “may.” According to the Environmental Protection Agency and the Department of Energy, it does take longer for the engine to warm up and reach an optimal driving temperature in cold weather, but it shouldn’t really take a study to know that. It is also important to note that cars do have worse fuel economy when it’s really, really cold outside. So drivers can expect to get lower fuel economy when the “Arctic Blast,” “Polar Vortex” or whatever buzz word the weather forecasters use to describe an extreme winter cold spell hits — at least for the first couple of minutes or until the engine heats up.

However, this doesn’t mean that warming up the car will help save fuel — because gasoline will be used to warm up the engine, and hence, drivers are not really saving anything. In fact, driving the car will warm up the engine faster than allowing it to idle anyway.

This is why auto experts today suggest that drivers should warm up the car for no more than 30 seconds. Some automotive experts even argue that if the car is started up and idled, in addition to the fuel that is potentially wasted, it could actually cause some problems.

If the engine is not under load yet fuel is actually going down into the cylinders and the engine is cold, there is the possibility of a phenomenon known as quench, where the fire is outside the cylinders. This can contaminate the oil much faster, increasing the need to change the oil sooner. This can also affect the lubrication of the engine as it is warming up, which is why many experts say with modern cars drivers shouldn’t idle a cold car if possible.

So why has the practice of warming up the car continued?

“Some people still continue to idle cars because of habits,” Rathi said. “Considering how impatient millennials are, this is likely to become a thing of the past soon. It is just wastage of energy with no benefits to engine performance.”

Yet, it almost seems like the industry encourages people to warm up their vehicles — often times without even having to get into them.

“Several cars come with remote start, which comes in handy to pre-warm the car,” Rathi noted. “This is a comfort factor not related with engine performance.”

It is also one that could be illegal, depending on state or local community laws.

Many jurisdictions have laws that make it illegal to leave a car unattended while it’s running, but the use of remote starters is a significantly more complex issue. While the car may not be able to drive off if the remote starter isn’t present in the vehicle, there is the issue of the environmental impact of using such a device.

According to the EPA, today 31 states, as well as Washington, D.C., have regulations against idling a vehicle. As with many other laws, these vary greatly, so drivers — and shop owners — should confirm the laws specific to their state and city. Even in states that don’t have laws on the books about idling, many cities do.

These laws usually have fines, which can be $100 or more. California, as an example, has a $750 fine for the first offense for idling a truck — but that is for letting it run 30 minutes or longer. The District of Columbia may also be among the most stringent when it comes to anti-idling laws. Drivers of diesel-powered vehicles who idle for more than three minutes — five minutes if temperatures are below 32 F — can be punished by fines not to exceed $5,000.

Many states do offer exceptions when temperatures are exceedingly cold — perhaps lawmakers don’t want to sit in a cold car any more than anyone else — but it is recommended to err on the side of caution.

Even in states where the idling isn’t an issue, leaving a car unattended while running could get a driver in trouble. Nick Taylor of Roseville, Michigan, found this out in 2017 during a cold snap when he received a fine for running his truck in his own driveway with the keys in the ignition. Taylor had run to the grocery store and only stepped into the house for a minute, but it still cost him $128 to pay the fine for leaving the vehicle unattended.

With all this in in mind, do some research on the idling laws in your community, and share your findings with customers before the next cold snap hits.