Old habits die hard, and one of the oldest—still rigorously enforced by many drivers—is that "warming up" the car for a few minutes is necessary to avoid some kind of unspecified damage.

But idling is totally unnecessary, which is why many communities have enacted ordinances against the practice. Don't take my word about idling being ineffective, but do listen to my mechanic, Rob Maier, who runs Maier's Garage in Bridgeport, Connecticut. He says, "You don't really need to idle your car, because of the efficiency of modern fuel injection, which eliminated carburetors and chokes. The only reason to let the car idle at all is to get the oil circulating, but after 30 seconds that's a done deal. My truck has 150,000 miles on it, and I just throw it into gear and go."

Here are some quick facts and tips that should put the idling question to rest:

1. Driving Warms the Car Faster than Idling.
If your concern is not the health of the car, but simply your own creature comforts, Bob Aldrich of the California Energy Commission points out that "idling is not actually an effective way to warm up a car — it warms up faster if you just drive it." The coming electric cars, such as the Nissan Leaf, will incorporate a wonderful feature that allows the owner to use a cellphone to tell the car (which is plugged into the grid) to pre-warm or pre-cool the interior. No idling necessary.