Whether you're sitting in traffic or starting up your car on a cold, winter day, idling is just a waste of fuel -- and it's actually bad for your engine. Expert advice varies on when it's better to shut off the engine than to idle. Some say that if you'll be idling for 10 seconds or more, you're better off just shutting off the car until it's time to move again. Others say that a minute of idling is OK, but after that you're wasting fuel. Whether you take the short or the long estimate, once you start paying attention to idling, you might be surprised at how often you do it.
Warming up the engine is one of the most common culprits when it comes to idling your car. Modern engines don't need to be warmed up when the weather is cold. In fact, driving will warm up your car faster than idling in the driveway, so your car's heater will actually start working faster if you just hit the road.
That's fine in winter, but what about getting better mileage in the summer?