It generally looks like a great idea using it as far as it concerns fuel consumption and gas pollution... but, does it really consume less fuel. I ask cause i heard that when the car starts it consumes a high amount of fuel, higher perhaps from what it saves when the engine automatically stops.
Is there a way to measure how much fuel is saved when engine turns off?

 

The typical answer is that if the engine is off for at least 30 seconds then you will save fuel.

 

And how did that 30sec come up? Is there some test that this 30sec is based on?

 

According to the American Society of Mechanical Engineers (ASME), restarting the engine takes as much fuel as 6 seconds of idling with the A/C on.

http://sections.asme.org/florida/ASM...thbusters.html

 

That sounds closer to what I've heard, which is 10 seconds.

 

Thanks for this! My friend was saying something crazy like it costs a dollar to start your car and i wouldn't believe him.

 

Just got this months Car and Driver. They test out all the myths and facts about getting good gas mileage. Skimmed it but haven't read it yet, looks interesting.

 

Sounds like a very interesting article, let us know what they say. Perhaps scanning the article and posting it here would be great for us non US residence, if you have the time that is!

 

You still haven't pinpointed us where you have heard or read this!

 

I don't remember, sorry. Does it really matter? 6 seconds, 10, 30, whatever. How much fuel do you really think you use idling for 6 or 30 seconds?? My answer is less than 10 cents worth. Anybody have a more exact answer, or a more exact reason why we even care this much about 10 cents? If I wanted to be this much of a tighta$$ then I would have bought a Yaris.

 

That website that Calmante provided for you would answer your question; they estimate that "six seconds" equals starting fuel
and 'if you could avoid ten minutes of idle at stoplights, you would save a quarter'.

I will only shut off when I expect several minutes stopped and a lot of that is just that I still enjoy watching the [START] button work.

 

Why not learn to use a feature correctly since its there? Why be indifferent to technology i have already payed?

 

Are you in Europe or the UK? There is no start/stop feature on US models, as far as I know.

 

Im in Europe!

 

That may be why you're getting some unusual responses. There is no auto stop/start here in the USA.

 

If you did a lot of stop-and-go driving, or had a lot of stoplights on your daily commute, the auto stop/start feature would increase your mileage. It also cuts down on vehicle emissions. As it's not a US feature, it would only be speculation to guess how big a MPG boost is possible. As long as it doesn't interfere with the function of the car, I don't see any reason why someone wouldn't use it if it was available as standard equipment. It may be only a few cents worth of gas saved each time you're stopped. but with typical city and suburban traffic, that's more often than you might think.

 

What about the increased wear-and-tear on the car always starting and stopping the engine? I'd like to see that cost factored in along with any fuel savings.

I doubt the MINI's engine is designed with frequent start/stop cycles in mind (unlike, say, a hybrid's engine).

 

They supposedly have a beefed up alternator which is supposed to be able to deal with that. Someone with more experience on the matter could elaborate.

 

Start/Stop technology is much more than just an on/off switch. It's a completely different starter (sometimes an additional one depending on the system), disgned to start quicker and last longer, a bigger alternator (sometimes) and very complex monitoring to determine if it can shut off, for how long, batter state of charge, electric load, etc, etc.

The simple fact is that engines are very inefficient at idle and fuel savings are very easy to measure. Most standard emission/fuel economy cycles have idle periods in them (just like most commutes do) and if you aren't burning fuel during them, you get better economy.