That is a good point. There is a tremendous amount of gas to saved by avoiding making others stop by getting going. The real problem is the clueless that can’t be bothered to pay attention.
Out of curiosity, where do you live? I can’t say I’ve ever seen such a sign in the U.S.
The OP may wish to visit the CleanMPG site. You can learn all you want about saving fuel while driving there, and what to avoid, like coasting downhill with the engine off in an auto.
Keep in mind that the UK uses imperial gallons (1 Imperial gallon = 4.54609188 liters, via google calculator) versus the US gallon (1 US gallon = 3.78541178 liters). This gives a conversion rate of 1 US gallon = 0.832673839 Imperial gallons. Carrying this through to Novelty Bobble’s example of 60mpg gives a US equivalent of 49.9604303 mpg. Still incredibly good, but not necessarily the eye-popping numbers you see at first-glance.
There is a useful calculator here for future use, if you don’t care to do the math yourself:
I’ve definitely seen signs at certain rail crossings – a particular category of red light 
– in metropolitan Chicago advising drivers not to idle – that is, to turn off their engines. For instance for Chicago Dopers, there are such signs in Des Plaines where the Union Pacific freight line (NOT the Metra line) crosses River Road between Rand and Golf Roads.
I say “advising” because I don’t recall off the top of my head if they indicate that idling at that location is illegal (stating a fine, citing a Vehicle Code section or ordinance, etc.).
I just watched a CNet video review of the new BMW 328i with this. I had to rewind it to confirm that the car is NOT a hybrid. These systems are stupid. They’re an example of ‘collective’ gas savings, IOW they’d be able to say something like, “If everyone’s car had this we’d save 50 jillion gallons of gas a minute…” yada yada yada. But on an individual basis you’ll never notice any savings. The Wiki article claims an average savings of 5-10%, but I really really doubt that figure.
The guy reviewing the car said the system was obnoxious and annoying and his favorite feature was the button that turned it off!
Here’s a local example. That sign is at a rail crossing too, but they’re also common at regular traffic lights in cities.
On average, how often do people stopped at red lights experience an emergency which would result in the loss of their health or lives, but which loss they had the ability to avert by driving away in the first couple seconds? By comparison, how often do they breathe in air polluted by automobile exhaust, what long-term effects does this have on their health, and how much could the air quality (and consequent general health of the population) be improved by having most people shut off their engines during longer stops?
Thanks for the link to the calculator.
I’m very pleased with the gas mileage I currently get in my Honda CRZ. I only have to fill up once a week. Compare this to the 2.5 times per week in my previous Toyota Solara.
If you’re driving on surface streets for a goodly part of your trip, then 5-10% lines up with what I see when I do this manually.
If it’s interstate superhighway for your entire trip, it won’t help.
I’m pretty sure this could save over 10% if your entire trip was stoplight to stoplight.
I’ve never seen that tupe of sign, and it seems short sighted as it appears like technology will take us there anyway.
Exactly. Why ask people to engage in environmentally friendly, pollution-reducing behaviour now when we can just wait twenty years for everyone to get a new car that does it for them?
It should be done more often. The down side is time required to recharge a battery after a start. IOW batteries typically take something like five minutes to recharge.
If the technique causes excessive wear (ie to the starter), then the car was defective when purchased. Restarting does not do damage or excessive wear to any other parts. Actually idling is harder on an engine.
One additional advantage. The brake system has vacuum assist. If that system is slowly leaking, you will learn of that failure when the brakes suddenly become stronger when restarting.
By doing that technique and others, I maintain gas mileage well above 30 MPG (even on local driving) on cars only rated for 28 MPG highway. People don’t realize that a car consumes gasoline at idle equivalent to when an engine is at something like 1500 RPMs. Idling is that wasteful of gasoline. Is a period of highest pollution. And causes increased wear to an exhaust system.