Can Car Talk Convince People to Stop Idling? A Reader's Plea

Dear Car Talk

Dear Car Talk | Jul 28, 2015

Dear Car Talk:

I write today to ask that you clarify the role of idling when it comes to gasoline cars, diesel pickups and large, over-the-road commercial vehicles. All the time, I see people sitting in their vehicles on a perfectly beautiful day, reading their mail at the post office, with their engines running, windows down or not. I see diesel pickup owners -- and there are a lot of them in Texas -- who will leave their trucks running, again in good weather, while they go into the convenience store or post office.

Even more personal is the intrusion of an 18-wheeler into our neighborhood, which is against the restrictions, but no one is sufficiently motivated to call the authorities to correct the situation. The most annoying aspect of it is the 30-plus minutes of elephant-rumbling idling that takes place prior to his departure and upon his return. I thought all this idling was basically unnecessary, "fuelish" and damaging to the engine, not to mention harmful to the environment. I hope you can address this to a national audience, as it would have potential to do a lot of good. Thanks.

-- Patrick

You're right about everything except harming the engine, Patrick.

These days, with fuel injection and computer engine management, cars and trucks can idle until they run out of gas without doing any extra damage to the engine (assuming the cooling system is working properly). Idling does add wear and tear to the engine --anytime the engine is running, you're decreasing the useful life of the oil and slowly wearing out parts. But it's no more harmful than driving.

Unlike driving, however, idling is a complete waste of fuel. It also increases pollution, by a lot. And it's entirely unnecessary. Modern cars can be driven immediately once they're started.

That's the best, and fastest, way to warm them up.

There are exceptions. If it's 3 degrees out, 30 seconds of idling to allow the oil to circulate is a good idea. And you'd want to drive at a modest speed, even after that, for a few minutes until the engine is up to operating temperature, rather than jumping right on the highway and flooring it. But 99 percent of the time, idling does nothing to help your engine.

It can improve your comfort -- which is where you're going to have a harder time persuading people to give up their idling. If it's 98 degrees out, and someone's waiting for her husband to finish shopping for the latest radial arm saw with the optional butt scratcher at Tools R Us, you can see why she might want to have the air conditioner running. But even then, she can turn off the engine, and when it starts to get uncomfortable, she can turn it back on for a few minutes to cool things off. Or how about this for an idea: Park in the shade!

Likewise, if it's 3 degrees out, a lot of people want to warm up their cars until the leather seats have thawed enough to conform to their butts, rather than feeling like rocks. And again, it's hard to argue with that, if that's how you want to spend your gas money. But I would point out that a car warms up faster when it's being driven, compared with sitting in a driveway.

On the other hand, your neighborhood trucker has no justification for running his cab for half an hour before or after driving it. Some diesel engines with turbo-chargers call for three to five minutes of idling before shutting down, to allow the turbo to cool off. But nothing calls for half an hour. And increasingly, jurisdictions are passing regulations prohibiting cars and trucks from idling, mostly because of the pollution it generates.

So my suggestion would be to have a talk with your trucker neighbor. Tell him you know he's just trying to make a living and you want to be a good neighbor, but the idling is too much. Tell him you'd be willing to overlook the regulations that prohibit 18-wheelers in your neighborhood if he'd be willing to limit the idling to no more than five minutes on either end.

Or, if he's a lot bigger than you, leave a note on his windshield, and sign it from another neighbor you don't like, then run. Good luck, Patrick.


Get the Car Talk Newsletter