Report: Letting Your Car Warm Up in the Cold Could Be Illegal in Your State
Thirty states, plus Washington D.C., either restrict extended idling or ban it completely.
It's tempting, and sometimes even helpful, to start your car and let it idle while you scrape ice and clear snow off it (you do clear all the snow off it, right?). Also, it's convenient to get into a car that's already warm and comfortable—but what you may not have known is that this could be illegal where you live.
No, the government isn't trying to make fun and comfort illegal (at least, not this time). An idling car creates pollution while getting the worst gas mileage possible—zero miles per gallon since it's not moving. Additionally, a cold engine doesn't run as efficiently as a warm engine, so it's actually spewing more pollutants into the air than normal while warming up. Though it may cause the occupants a little discomfort, it's actually best to start driving as soon as possible after starting the car, since putting a load on the engine helps it warm up faster and become more efficient.
According to a recently discovered EPA document, thirty states plus the District of Columbia currently have laws governing extended idling times for motor vehicles. The document lists both state laws and those of local municipalities. For example, my home of Massachusetts prohibits idling for more than five minutes, with exceptions for delivery and public service vehicles. That's generally enough time to wipe the snow off your car, so that's what I do and stay legal. The cities of Cambridge, Chicopee, and Peabody (pronounced "PEE-ba-dee," not like Mr. Peabody of Rocky and Bullwinkle) also have their own laws about idling that are more strict than state restrictions.
If it gets cold where you are—and these days, that's pretty much the entire United States—check the EPA list and familiarize yourself with what you are and are not allowed to do. This goes particularly if you live in a southern state that doesn't normally get this cold. The temptation to warm up your car may run afoul of the law without you knowing it. While you're at it, here's some other advice for keeping a car happy through winter.