Murphy's Law of Engine-Idling Duration
"If you leave your
vehicle's engine running during a delay in proceeding (traffic-jam,
road construction, accident-resolution, "stuck" red signal-light, etc.), you will be sitting there for many minutes, just wasting gas. The instant you
turn the key off and climb out of your seat to stretch, however, THAT'S when the line of traffic will begin moving again, and thus you will have shut off your engine "for nothing", AND you will now be holding up everyone behind you while you hastily hop back into the driver's seat and re-start the engine so that you can move forward again."