The most abuse put on the motor is during start ups. So I probably wouldnt agree with the turning it on and off every light.

During warm up the car still idles 14.7 a/f ratio. Havent you guys ever used a wideband before? Only difference with warm up is your idle will be slightly higher, hence why you will burn more fuel.

The car might require more fuel to start up, but like many said that is only for a couple seconds. And its not like your motor is dumping in as much fuel as going WOT racing. Standing their and idling just lowers your mpg because your burning fuel and traveling 0 miles.

Shut off the car if your going to just stand and idle more than a minute. Otherwise if your at a light or drive through, dont bother.

 

hybrids have the benefit of not relying on a starter to fire up the engine again. once te electric motors get scooting it's not big task to put fuel and spark down the cylinder.