Turn off that engine

I USED to think that standing still in traffic with the engine on wasn’t so bad. Heck! Everyone was doing it. But then my dad saw me letting my engine run while I stepped outside for a few seconds – he started lecturing me about how leaving my engine idling for more than 30 seconds was a waste of gas. I countered that turning off the engine and turning it on again would be a waste of gas.

Turns out I’m wrong. The website of the California Energy Commission states that, for every two minutes of idling, a car uses one mile’s worth of gas. A driver normally idles for ten minutes on average – so that’s five miles wasted, in theory.

The CEC recommends that if you know that your car will be idle for more than 30 seconds, turn off the engine. According to them, ten seconds of idling burn more fuel than restarting your car’s engine. They also state various car myths, like the myth that the engine should be warmed up before driving. Idling doesn’t do much for your car in terms of waking it up. It doesn’t make mad-mad like people do. The best way to warm up your car is to just drive. However, if you turn on the air conditioner immediately after you start your car, there’s a risk that you’ll inhale some carcinogens which may help cause cancer.

The CEC says that excessive idling can actually damage your engine components, including cylinders, spark plugs, and exhaust systems. Fuel is only partially combusted when idling because an engine does not operate at its peak temperature. This leads to the buildup of fuel residues on cylinder walls that can damage engine components and increase fuel consumption.

Frequent restarting has little impact on engine components like the battery and the starter motor. Component wear caused by restarting the engine is estimated to add $10 per year to the cost of driving, money that will likely be recovered several times over in fuel savings from reduced idling. The bottom line is that more than ten seconds of idling uses more fuel than restarting the engine.