One of the most common misperceptions about winter driving is you must idle your car’s engine before driving. In fact, a recent study showed that the majority of Americans believed idling your engine was a good thing and that you should idle for about five minutes. The reasons people give for why this is necessary range from fuel economy to engine health, but according to science, there’s really only one good reason to idle your car: Nobody likes climbing into a freezing cold cab for their morning commute.
Like most myths about cars, there are elements of truth to idling your car. In the old days, when cars relied on a carburetor to get the right mix of air and fuel, a cold carburetor could mean stalling your car—only when they were properly warmed up did they function properly. However, in the 80’s and 90’s, auto manufacturers did away with carburetors in favor of electronic fuel injection. Unless you’ve got your antique out for a spin on wintry roads, there’s no advantage to idling.
Further, it’s true that cold engines and cold weather cause a marked dip in fuel efficiency. In addition, it takes much longer for a car to warm up and reach ideal driving temperatures when the snow flies. But the fact of the matter is a car actually heats up quicker while it’s being driven, not while it’s sitting there in your driveway with the defrost blasting, and there’s precious little you can do besides heading south to raise the outside air temperature.
Experts say a good idle time is about 30 seconds, which is a far cry from the five minutes many Americans think is necessary. Your car doesn’t need any more time than that and, in fact, you’re costing yourself a lot of wasted gas. The only good reason to idle your car is personal comfort. Just know that it comes with a cost.