Idle Myths

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There are many common misconceptions people hold around idling.

Pollution emitted from idling vehicles is insignificant to my health and to the environment.

One minute of idling produces more carbon monoxide than the smoke from three packs of cigarettes. The toxic air pollutants emitted from idling can impair our lungs and heart, and exhaust fumes have been linked to asthma, decreased lung function, cardiac disease, cancer, and other serious health problems. Kids, the elderly, and people with respiratory ailments are especially at risk. An hour of idling releases 11 pounds of CO2 into the air.

Idling is good for my engine.

An idling engine is not operating at its peak temperature, which means that fuel does not undergo complete combustion. This leaves fuel residue that can deposit on spark plugs and increase fuel consumption by up to five percent. Also, water condensation in the exhaust system can reduce the system's life.

Eliminating unnecessary idling won't save me money.

One hour of idling can burn up to one gallon of fuel. Based on the average of 16 minutes of idling per day, most drivers end up wasting up to five tanks of fuel per year. Avoiding five minutes of idling per day can save upwards of $35 every year. When you idle, you get zero miles per gallon.

It wastes more fuel to restart my vehicle than it does to leave it idling.

For cars with fuel injection (which includes almost all vehicles built since the late 1980s), idling for even 10 seconds uses more fuel than restarting the engine. In fact, Ford Motor Company recommends that drivers "turn the engine off when stopped for more than 30 seconds to save fuel and reduce exhaust emission."

I should turn my engine off at traffic lights and stop signs.

While your vehicle is idling during short stops for red lights and stop signs, this is not a safe opportunity to turn your engine off to protect air quality.

Shutting off and restarting my vehicle is hard on the engine.

Again, Ford Motor Company recommends turning the engine off, even for stops of 30 seconds, to save fuel, money, and air quality. They have said "frequent restarting has little impact on components that include the battery and starter motor." Component wear caused by restarting the engine is estimated to add $10 per year to the cost of driving, money likely to be saved many times over due to fuel savings from less idling.

I need to warm up my car for several minutes in the winter.

Idling is not an effective way to warm up your vehicle. Modern engines only need to warm up for 30 seconds on cold days. Idling is a slow and ineffective way to warm up your engine. Furthermore, idling your car for several minutes before driving crease extra air pollution, since your car's catalytic converter is not effective at reducing the pollution in your car's exhaust until it is sufficiently hot - generally only after driving a few minutes. The best approach is to only idle for 30 seconds, and then just drive gently for the first few miles.

And whatever you do, don't leave your car running unattended. During the winter months, thieves are on the lookout for cars left idling in driveways, alleys, and at convenience stores - and they're ready to hop in and drive away in your car!