To answer the OP’s 1st question, yes it will save gas, and to address everybody else, no it won’t make your car suck, lengthen your stay at lights, or kill your starter. So, MikeinNH was kind of correct, if it worked, there would be one out there. And there is. Case in point, besides the obvious hybrids…
Nice! That should settle the bet. The atricle states that shutting off the engine at stop lights and in traffic jams will increase fuel economy 8% when it happens automatically.
To the OP: Don’t fall for the faulty logic of “If it worked, every car would have it already.” It takes more than logic to bring a product like this to the market.
It’s an interesting post. BMW has gone to a lot of trouble to improve gas mileage if you can believe the numbers. Conversion to front drive would make the BMW system appear stupid by comparison if you include highway driving. I do understand, however, BMW’s reluctance to convert to front drive because of the handling advantage of rear wheel drive. Note too that the system apparently is provided only for a manual transmission car.
People in Europe, who pay WAY more than we do for fuel, do this regularly.
… and people in India drive around with their headlights off at night because they think that will save them gas. Just because it’s a common belief doesn’t mean it’s true.
Here’s my $.02. Even if you watch the other lights and have it well timed, there’s always going to be a few times where you don’t start the car in time. Then you’ll have to accelerate hard to avoid holding up traffic, which is what REALLY eats gas in stop-and-go traffic. Even if it only happens two or three times a trip, it’ll eat up whatever savings you get from not idling.
I suppose in some parts of Europe, where they have the “racecar” signals that tell you right before the light turns green, it would be easier to do. Also, most European cities are not laid out for cars at all, and consequently even small cities have really bad traffic, where you can reasonably expect to be stopped for a few minutes at a time. There’s only a few places like that in North America.
You will save gas. But not enough to overcome the cost and hassle of a replacement starter and the labor if you cant do it yourself.
As far as safety, I see it a bit differently, but still wouldnt do it. If someones coming towards you, and the traffic is that bad where youre going to be sitting that long, where are you going to go? And at least around here, Ive never heard of a rear end collision because someone does not take off from the light quick enough. I suppose they mow over pedestrians who cant get across the street fast enough too.
My biggest concern would be sitting there with no brake lights on, thats an invitation to get rearended. I do shut off the engine when Im sitting in road construction, or waiting for the local drawbridge, but I at least wait for a car to get behind me and stop before doing so and taking my foot off the brake.
Heck Ive been rearended at a traffic light once, having been sitting there for at least 10 seconds with the brake lights on. And a few other times not at traffic lights.
My rough guess is that a car uses 2/3 gallon per hour idling, or 0.67 GPH. This is based on a CarTalk caller from Minnesota where he said that his car uses 8 gallons of gas when left idling all night long (which I take to mean 8pm - 8am, or 12 hours). A 90-second red light is 0.025 hours. 0.67 GPH * 0.250 Hours = 0.0167 gallons. In order to save 1 gallon of gas you would need to do this 60 times.
To get accurate numbers, you’ll need to replace 0.67 GPH above with your car’s actual numbers. The only way I can think to do this is fill it up with gas, let it idle for 5 hours or so, fill it up again and see how many gallons got eaten / 5.
In good conscience, I must say: Please do not do this.
Ten times faster.
My biggest concern would be sitting there with no brake lights on, thats an invitation to get rearended.
Whenever I’m stopped at an “unusual place” due to construction, school bus, etc., or I’m forced to go more than 10 mph under the posted speed limit, I always turn on my 4-way hazard flashers. It does tend to wake up drivers charging up behind me and dreaming while yakking on their cell phones. I don’t normally do it at a light or stop sign, unless there’s something unusual going on.
My biggest concern would be sitting there with no brake lights on
You can (and probably should) leave your foot on the brake, and that’ll keep the lights on.
While you will save gas, most cars, especially diesels, spew particulates the worst when starting. And that’s probably the cause of many kids’ asthma. Drawbridges, accidents, and Interstate parking lots are good reasons to turn off the engine, but red light cycling is probably bad for the environment.
Clearly, we have a safety issue here, as well as inevitable delays as drivers try to start their cars when the light turns green. The poster who said “green means ‘go’, not ‘start your engines’” said it all. My city has an official green program, urging citizens not to idle their cars unnecessarily, and putting strict control on their own employees. However, not a word about shutting off your engine at a red light. They know the chaotic situation that will result. The police department is also horrified at the thought of all the rear-enders that could result.
HUH? what are you talking about?
Note that in at least some countries in Europe where turning off the engine at lights is supposedly a common practice, the stop lights give the folks waiting on red signals a warning when it’s going to turn green. Basically, the yellow comes on for both directions. So, you have time to start the motor before the light actually turns green.
Now, with that said, I have driven in Europe. Most recently in England, France, and Italy, and have never noticed anyone doing this engine shutdown thing. Maybe it’s mostly a German practice, but fuel is certainly expensive in all of Europe.
In Malaysia and some other Asian countries there is a countdown light to zero(like Times Square on New Year’s Eve), not for shutting the engines off and turning back on, but to keep drivers from jumping the lights. However, it could be used to warn when the car had to be ready to move.
I don’t think the warning that the light is going to change from red to green is specifically for people who turn their motors off, I’m just saying it would make it easier for those who did to know when to restart. As far as I know the lights in France have worked that way for a long time.
“People in Europe, who pay WAY more than we do for fuel, do this regularly”
I’ve never noticed this except bus drivers do to reduce pollution and cut their driving hours down. Also they don’t PAY more for fuel than we do but pay way more taxes on the fuel than we do. The taxes go to pay for their social programs.
At any rate not a smart idea for the reasons already stated.
You know, I actually noticed this myself-- in Atlanta the traffic was super bad one summer so I took to putting the car in neutral and setting the brake (which most people did, so I wasn’t worried about getting rear ended). In the end, I started being un-lazy enough to just keep my foot on the brake instead of letting it idle in neutral or park. (This was pre-Hyundai, really old car, so the mileage difference was much more noticeable.)
In France and the Netherlands not yet (alas). But in Denmark yes for sure.
Giving more information to the drivers (whether in the form of the “race car” signal where the light turns yellow again before turning green, or with a count-down) cannot hurt can it? Then one can let people decide whether they want to shut their engine off or not. I am still puzzled as to why this (the race car option) is not implemented everywhere. The bulbs etc are there already. Isn’t it just a matter of reprogramming the lighting sequence? Why does it take so long so implement a great idea? Who is benefiting from more gas being burnt?
In more and more cars in Europe, the auto-shut-off feature is present. And since cars are now smarter, they tally up the total amount of seconds of idling saved. I guess one can go around such cars and divide the number of seconds saved by the number of km ridden, use the average fuel consumption and get more statistics.
About shutting your engine down in other situation, in the Netherlands, when a bridge opens up to let the boats go by, traffic is stopped (even on highways sometimes 
) and a sign request people to shut off their engine (cars, but also scooters). But maybe it is more to give a greater chance of survival to the people on bicycles waiting there too than to save fuel or the reduce emissions. It is nice though. Suddenly all noises stop and people are forced to watch a slow boat go by.
Of course, technological advances may have changed things since 2007 when the original question was asked… 
In any event, I can safely guarantee that any response to the original poster will not be read by him/her.
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My $0.02:
- Shutting down WILL save YOU fuel. A modern car, with a warm engine, will jump out of “open loop” almost immediately after restart, and the additional startup burn is but a few drops.
- Shutting down MAY or MAY NOT save you money. You have to weigh the “starter and battery wear” (and there IS some) against the “saving fuel” money. This makes a “breakeven point” that is different for each vehicle (how robust is the starter, how easy is it to change, will you do the work, or hire it out, etc.)
- Shutting down MAY increase pollution. If you shut down long enough to let the cat cool off, then startup will burn dirtier, until cat re-warms…so you might be burning “less fuel, less cleanly.”
- Shutting down MAY burn EXCESS fuel (considering all motorists) even if YOU burn less fuel. If you’re not “Johnny-on-the-spot” getting the engine fired back up when the light turns green (of if your starter is suspect), you’re delaying everyone behind you, which means THEY spend MORE time idling, thus burning more fuel. So even if YOU are saving fuel, society as a whole may not be!
ARRGH! The necropost strikes again! (Totally missed it guys; sorry…)
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