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Concentration of CO2 in the Atmosphere

Vehicle Idling in the Winter

Idling vehicles waste fuel and money. Idling also has a negative impact on our health and environment. (Photo: Flickr/MN Pollution Control Agency)

Wayne Michaud

Ugh, it’s cold outside! And not only that, it snowed four inches last night. But, no matter, I have to drive the pickup truck into town to do a few errands. So, let’s start her up and let it run for ten minutes or so to get the engine running nice and smooth, the interior toasty, and melt off some of the snow and ice as well.

The above scenario is fairly typical among us who drive internal combustion engine (ICE) vehicles during winter. Many drivers are unaware of the harm and waste of discretionary idling—that’s idling when parked—a largely unnecessary practice, even in winter. Let’s take a closer look as this has an impact on our vehicles, our health, the environment, and the law. Plus, we’ll explore ways to minimize the idling impact.

Some facts on the impact of idling related to fuel use and maintenance costs:

Idling a light-duty vehicle (compact, sedan, SUV, most pickups) burns 0.2 to 0.7 gallons an hour; for heavy-duty vehicles, one gallon an hour or more.

Ten minutes of warm-up idling can cost $40 to $150 annually, depending on engine size.

Idling a light-duty vehicle for more than ten seconds uses more fuel than shutting off the engine and restarting (30 seconds for heavy-duty vehicles).

According to a U.S. DOE study, restarting up to ten times a day will not shorten starter life. Ever see an UPS truck idle while a driver makes a quick delivery? Probably not, as UPS’s strict idle reduction policy reflects the fuel savings benefits, over starter wear.

Excessive idling causes needless engine wear. Besides the accumulation of “ghost” miles, the engine does not operate at peak temperature which causes carbon soot buildup on engine parts and the need of more frequent oil changes.

Another reason not to idle in Vermont, and in New Hampshire and Massachusetts as well, is that these states have laws that restrict the idling of all motor vehicles, not just heavy-duty diesel trucks and buses. Depending on the state, the law restricts idling to five to 15 minutes in any 60-minute period, with exemptions.

So, what is the best, most efficient way to warm up a car in winter? First, be prepared for the cold! Clear off any snow and ice before starting the engine. Excepting families with frail elderly or infant passengers, from 32º to about 10º Fahrenheit, start the engine, blast the defroster, and let it idle for up to 30 seconds (in colder temperatures, one to three minutes). This will allow engine oil to fully circulate. Then, only if defrosting is adequate, drive the car under light to moderate acceleration for a minute or so before operating normally. These quick stationary warm-ups will allow the catalytic converter to begin its function of minimizing tailpipe toxins once the vehicle is traveling. The engine will get up to peak operating temperature faster. The car’s heating system will work better. Yes, you will be cold for a few minutes, but you’ll treat your car right, save some money, improve local air quality, and reduce some CO2 emissions each day. Here is a tip: consider investing in one of the several types of engine block heaters available, which will make starting easier on cold mornings.

Idling vehicles can have an impact on our health. Even modern ICE vehicles can emit harmful tailpipe toxins in circumstances such as warmups, in extreme temperature ranges, and when in a caravan of vehicles such as at school drop offs and pick ups. The U.S. EPA states: “Idling vehicles contribute to air pollution. Monitoring at schools has shown elevated levels of benzene, formaldehyde, acetaldehyde and other air toxics [sic] during the afternoon hour coinciding with parents picking up their children. Children’s lungs are still developing, and when they are exposed to elevated levels of these pollutants, children have an increased risk of developing asthma, respiratory problems and other adverse health effects.”

School buses can be even more of a concern as their diesel exhaust contains higher levels of nitrogen oxide and fine particulates that can get into our lungs. New England states regulate the idling of school buses on school grounds to varying degrees. In general, they must warm up away from school buildings and not idle while children board or exit the buses at school, though there are exceptions for defrosting needs and in extreme cold.

What can we do to minimize the negative impacts of idling? Behaviorally, it’s mostly a matter of following the advice in this article. What do we gain each day? Saving some money, being kinder to our cars, improving air quality, and reducing our carbon footprint. What do we sacrifice each day? About five minutes of comfort. Technologically, think of low- to zero-emission vehicles, the future of transportation. Right now, full hybrids are a good choice to minimize discretionary idling while leaving the engine on. Plug-in hybrids will all but eliminate idling and greatly curtail gas use. While all-electrics can have battery-range limitations in winter, by using no gas, no oil and emitting zero tailpipe toxins, they are a great choice for short to medium commutes.

Wayne Michaud is Executive Director of Green Driving America Inc., a non-profit that educates on transportation efficiency. The organization is based in California with a branch location in Vermont. Michaud headed Idle-Free VT in Vermont from 2006 through 2016.

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