You’ve all heard it. No, it’s better for the engine if I let the car idle. It’s more efficient if I let the car run.
I remember, years ago, reading that it was only more efficient if the car was idling for less than ten seconds. Today, thanks to some required class reading & a bit of extra research I am happy to report that it’s true: If you’re idling for more than ten seconds, you’re burnin’ up your gas, your engine & your atmosphere. This anti-idling primer sums up some stats that I enjoy:
To most, idling a car may seem fairly innocuous, but it is actually detrimental to the modern automotive engine, wastes gasoline, and is often done based on mistaken assumptions or outdated logic, or simply out of
habit. Each day, Americans waste approximately 3.8 million gallons of gasoline by voluntarily idling their cars.
Maybe we can’t all shut our cars off at a stop light, but we can switch off at the ATM, in the parking lot, while talking to a friend in front of their house, while waiting in line at the MacDo.
While the general environmentalist gives the mark of 10 seconds until shutting the car off (without damaging the engine, I might add), the EPA still gives a more conservative estimate than you’d probably imagined: just 30 seconds. This applies to those cold winter mornings, too. As many sources* will tell you (including your knowledgeable mechanic), the best way to warm up your car is to drive it. Makes sense, right? With the modern fuel-injection engine, you can give the car 30 seconds to get going & then begin driving with no fear that you’ll tear up all that stuff hiding under the hood.
Want more technical info, to impress your friends & prove that you know more than how to use the dip stick? Throw this out there when they tell you that switching off the engine is doing anyone any damage, courtesy of Brendan Koerner at Salon:
[That argument] assumes that you started driving way back in the heyday of the carburetor, when engines started up with a big gush of fuel. …
Today’s cars use electronic fuel injectors, which rigorously control the amount of gas delivered to the engine when you hit the ignition. As a result, virtually no fuel is wasted during startup, and only a thimbleful is burned as the car roars to life. So forget about the 30-minute axiom you were raised on—the threshold at which it makes more sense to shut off rather than to idle should be expressed in seconds, not minutes.
Costly myths by Amanda Carrico addresses a lot of the excuses we give for letting our car run. The study also answers this big question: Ok, but how much does it really save to just shut the car off all the time?
1088.3 pounds of CO2 emissions each year. Per person.
Carrico found that the average person idled…
- for four minutes to warm up their car,
- for eight minutes while waiting in traffic, and
- for 3.7 minutes while just waiting for other things.
Based on the number of drivers and fuel prices in 2008, all of us just sitting in our cars accounts for 1.6 percent of all CO2 emissions in the States. Even following the EPA’s 30-second rule, we’d remove 15.8 million metric tons of CO2 each year. That’s a big number. I can’t fit it in my head, so it means almost nothing to me. Want to see a number that does mean something?
Those savings–that lack of idling–would save the States 1.8 billion gallons of fuel a year. That’s $5.9 billion dollars.
Alright. We are now fuel- & carbon-saving experts. I look forward to seeing your lights switch off in front of me when I sit behind you in the drive-thru at Burger King. (Thanks for your Morningstar option, even if it is microwaved, BK!)