Idling cars are the tools of the devil

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vehicle exhaust

Vehicle exhaust contains a number of harmful pollutants, including fine particulate matter, and it is increasingly the primary source of urban air pollution (courtesy of Wikimedia Commons).

Thus far, El Niño has more or less kept winter at bay here in Cleveland. Well, that’s all changing this week. I guess once Mother Nature heard an overgrown rodent said we were getting an early spring this year, she got pissed.

Winter is back with a vengeance. We’re going to see temperatures drop to perhaps their lowest point of the year this weekend, and forecasters are calling for five or six separate fronts to bring snow over the next week or so. All of this should help to cut into our substantial snow deficit. As of Monday, the National Weather Service had recorded just 11.2 inches of snow this winter, roughly 26 inches below normal. That deficit has already shrunk by one-fifth, and it will continue to decrease.

The return of winter means a few things. First, our profuse application of road salt – with all its inherent environmental consequences – means that everything will adopt a fine coating of sodium chloride. Second, those of us walking through the city will trudge through unshoveled sidewalks and try to avoid the ubiquitous puddles of filthy, half-melted slush, which could either be an inch deep or the bottomless pit that Ozzie Smith fell into on The Simpsons. And third, people will idle their cars left and right. The other day, I walked past a St. Ignatius security guard who was idling his car in a parking lot on Lorain Avenue. When I came back an hour later, he was still idling his vehicle, all the while straddling three separate parking spots (including a handicapped space).

Now, I see the appeal of vehicle idling in the winter, but I don’t really understand the level of passion that idlers bring to the table. A few weeks ago, our local ABC affiliate, WEWS, reposted an article on why drivers should avoid idling their cars during the winter. Within a few hours, the pro-idling commenter horde descended to inform the reporters just how wrongheaded they were.

I know – never read the comments – but individuals insisted that “this is the dumbest thing I’ve ever read. Warming up car by idle (sic) is very good” and “cold oil will destroy your engine.” And, of course, the coup de grace: “Stupid article with gas prices at a (sic) all time low I could careless (sic) if I waste gas warming up my car especially when the windows are frosted or frozen.”

Let’s assume for a minute that the U.S. Environmental Protection Agency and basically every other authority on this topic, including car-makers, know more about vehicle idling than random internet commenters. Can we marshal the available information to help dissuade some of these pervasive myths on idling? Of course we can. So let’s do that.

“Warming up car by idle is very good”

This one is perhaps the most common idling myth, and, like all good myths, there is a kernel of truth here.

The EPA says that, on average, cars get 12% worse gas mileage during cold weather. However, this was a much bigger issue for older model years, particularly those that employed carburetors. Modern fuel injection systems automatically adjust to exterior weather conditions. Furthermore, cars warm up twice as quickly when driven as they do while stationary. It may be nice to sit in a car that you warmed up with your remote start on frigid winter mornings, but you’re not doing your car any favors.

“Cold oil will destroy your engine”

No, no it won’t. Again, this myth is ubiquitous, but it’s highly out of date. Modern, synthetic engine oils do not need to warm up first. They can flow properly at temperatures as low as -40°F. It may have been cold as hell last February, but we still live in Cleveland, not Barrow or Yellowknife.

Beyond this, idling is actually harder on your car than driving it normally. While batteries commonly stall out in cold temperatures, idling does more long-term damage. As they idle, car batteries continue to expend energy to the car’s components. This process leads to deeper engine cycling, which forces the battery to discharge more energy during normal engine operation. Discharged batteries, in turn, produce less power; this means that subsequent engine starts will require even more energy and take longer, which will shorten a battery’s lifespan.

Idling is hard on cars in other ways as well. It is true that a number of vehicle components, such as the starter, are designed to last a set number of starts. This would seem to suggest that idling your car would place less wear and tear on a vehicle over time. But again, this is not true. According to Natural Resources Canada, idling your car for just 46 seconds is worse and more costly than turning it off and back. In addition to straining the battery, idling engines do not run at an optimal temperature, which leads to the incomplete combustion of gasoline. This leaves fuel residue in the engine – not to mention producing more pollution – and can cut fuel economy by around 5%.

“I could careless if I waste gas warming up my car”

Would that I were so wealthy. But let’s consider exactly how much gas this gentleman – who I assume is Rich Uncle Pennybags from Monopoly – is wasting by idling.

Every two minutes that a vehicle spends idling consumes the same amount of gas as driving two miles. The average vehicle spends 60-73 hours idling per year, which accounts for 5-7% of total fuel use. Based on information from the Argonne National Laboratory, if a person idles for 10 minutes per day, s/he can waste up to 30-50 gallons of gas per year.

The true costs of vehicle idling

But, if you’re familiar with anything I’ve ever written, I’m more interested in trying to figure out the social costs of our idling habits. If everyone in Cleveland idles so profligately, what are the effect on the larger scale? How might all of that extra, inefficient fuel use add to the costs of air pollution and climate change?

With that question in mind, I decided to do some back-of-the-envelope calculations. According to a 2009 study from Amanda Carrico and colleagues, the average American idles approximately 16.1 minutes per day. More than half of that idle time (8.2 minutes) occurs due to traffic lights, congestion, stop signs, and the like, so we’ll eliminate it. This leaves 7.9 minutes of idling per day – 4.2 minutes for warming up the car and 3.7 minutes while waiting (to pick some up one, in the drive thru, etc.).

Next, we need to determine the population of passenger cars in the Cleveland area. According to data from the Ohio Bureau of Motor Vehicles, there were 2,130,794 passenger vehicles registered in the seven counties that make up Northeast Ohio last year. Of course, not all of those vehicles will idle that amount each day, so I will adjust these numbers to reflect the percentage of the general population that reported idling for warming (48%) and waiting (46%) for more than 30 seconds at a time in the Carrico et al. study.

We now need to figure out how much pollution and fuel cars consume while idling. Fortunately, the EPA has provided this information, though they do not have estimates for particulate matter emissions (which are, by far, the most harmful conventional pollutant in vehicle exhaust).

idling emissions calculations

Annual vehicle idling emissions in the seven counties of Northeast Ohio (author’s estimates).

Using information from the US Department of Transportation (updated to 2015$) and the EPA’s social cost of carbon, we can estimate the total public health costs of these idling emissions per year.

idling cost calculations

Total annual costs of vehicle idling in Northeast Ohio (author’s estimates).

So, by my (admittedly rough) estimates, vehicle idling carries social costs of more than $58 million per in Northeast Ohio alone. While the vast majority of these costs come from wasted fuel, there are still nearly $3.5 million in air pollution related costs. I could go down the rabbit hole of trying to estimate the morbidity and mortality costs associated with these pollutants, but I’ll spare you the arm-waving wonkery. But let’s not pretend that this wasted fuel has no effects. Oil extraction has significant environmental consequences throughout the process from well to tank, and – given that is a nonrenewable resource – all of this valuable fuel could have been put to more productive uses. Waste is waste is waste.

As all the available evidence and my calculations show, vehicle idling is far from beneficial. On the contrary, is wasteful, costly, and illegal in many places. If this one small component of driving carries this large of an impact on our region, can you imagine the aggregate costs of our cars? Comfort is important, but it’s not everything. So turn the damn engine off next time. Your lungs and wallet will thank you.