Old habits are hard to break. 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detrimental to the modern automotive engine, wastes gasoline, and is often done based on mistaken assumptions or outdated logic, or simply out of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. While all
idling is bad for the car engine, this primer addresses only voluntary idling, which occurs when the car is not actually
being driven in traffic. (Of course, the best way to address involuntary idling, which occurs in traffic, is to buy a hybrid,
but we realize that most people are not yet ready to sell their conventional cars and replace them with non-idling hybrids.)
There are, however, easy steps owners of conventional cars can take to help the cause.
Myth 1: Cars should run in an idling mode for several minutes before being driven.
Wrong. Modern engines do not need more than a few seconds of idling time before they can be driven safely.
Moreover, the best way to warm up a car is to drive it, since that warms up the catalytic converter and other
mechanical parts of the car, in addition to the engine.
Myth 2: Each time you start your car you waste more gasoline than if you let it idle.
Wrong. Automotive engines do not operate efficiently when they idle. Experts say there is a maximum 10 second break-even rule. If you are idling longer than 10 seconds, both you and the engine are better off if
the engine is turned off and restarted.
Myth 3: Repeatedly restarting your car is hard on the engine and quickly drains the battery.
Wrong. Frequently restarting your engine does negligible damage to the engine and does not drain modern
batteries excessively. In fact, the opposite is true; idling an engine forces it to operate in a very inefficient and
gasoline-rich mode that, over time, can degrade the engine’s performance and reduce mileage.
When not actively driving, people tend to idle their cars largely for one of two reasons: either to warm up the engine
before driving or to avoid wear and tear on the engine in situations that require frequent restarting, such as drive-through
service lines, rail crossings, car wash lines, carpool lines, and departure from concerts and sporting events, or while
talking to friends or using the cell phone. By understanding the effects of idling and reducing the practice, you can
improve your car’s performance, save money, and reduce needless carbon dioxide emissions.