Re: Turn It Off.
 

The act of starting the engine uses up a little more fuel than idling the engine, but the amount will differ depending on the vehicle, and whether the engine is already hot. As a rule of thumb: If the car will be stationary less than a minute, don't switch off; between one and two minutes it won't make much difference either way; longer than two minutes you'll see the benefit from cutting the engine.

This policy is a monumentally stupid idea. The fuel saved would be far less than the fuel that wardens use to get from junction to junction to "police" this lunacy.

There are bigger savings to be made by preventing people from unnecessarily revving their engine. Not just when stationary, but also with drivers who race their car off from a standstill. The latter would be easy and cheap to implement, too. "Red light" cameras just need to be reconfigured to take three photos based on excessive acceleration.