I was taught as a kid to turn off lights when I leave a room and not stand in front of the refrigerator with the door open. I was also taught to idle my car to warm it up on cold mornings. I stopped that 5 years ago when I got a Volkswagen TDI because I read that it was bad for a diesel engine to run while the car was not moving, particularly if the engine was cold. When I was out with Bonnie on the bike last week we passed a truck idling. A few days later, in the same drive, a car sat idling. It made me wonder if idling the engine was necessary for gas engines and how much greenhouse gas is added to the atmosphere each year just from people “warming up” their cars. In fact, the engine should only be run for 30 seconds before driving. It is also best to turn off the engine anytime your car will be stopped more than 10 seconds.