In the summer, you can take a chance and run down to fumes. But in the winter, if you do get stuck or stranded, the engine will be your only source of heat. And you don't want to have to worry about conserving fuel and saving the planet right at that moment...you want to stay warm. You can run the engine indefinitely at idle to stay warm-or as long as you have gas. No harm will be done to the engine.

By the way, if you have an old jalopy, we suggest you crack open the window a bit if you are going to be idling the engine. Old jalopies are more likely to suffer from exhaust leaks and rust holes. This may not be a problem while you're driving because the wind is removing the exhaust as you move forward; but if you're sitting for a long time while carbon monoxide is slowly leaking into the passenger compartment, well, we could lose another listener. And we've only got six left!

Finally, if you are pulled over and stopped in the midst of a humungous snowstorm, be sure to get out periodically and remove snow from behind the tailpipe to keep it unobstructed.