How much time do cars need to warm up?

Here's a little factoid that I didn't know until recently: You don't need to warm your car up on a cold day for it to be safe to drive.

Apparently, this is a pretty widespread myth. For years, I've let my car run while I scraped snow and ice off the windshields, under the idea that the car needed to warm up before I drove it. Yet, what do you know? Modern cars only need to run for about 30 seconds before you can drive them.

And this is important. According to one of my colleagues here at NREL, you burn eight ounces of fuel for every five minutes your car idles. Considering the price of fuel these days (even if it is finally going down a little), letting your car "warm up" in front of the house will just cost you money. Furthermore, several states and cities now have laws about idling, and leaving your car unattended while it warms could actually get you ticketed. For more information about the effects and costs of idling your car, to "warm it up" or for any other reason, see the Hinkle Charitable Foundation's Anti-Idling Primer.

And for general tips about how to save gasoline, see Driving and Car Maintenance on the Energy Savers Web site!

Elizabeth Spencer is a communicator at the National Renewable Energy Laboratory, which assists EERE in providing technical content for many of its Web sites.