I avoid heavy traffic and time lights as closely as possible so that I never come to a complete stop at a light. Now I know why.
LOL, no problem. Iāve done it a few times myself.
If you drove a car with 500,000 miles, you wouldnāt be so inclined to shut the car off at every stoplight, especially when its below zero out. Saving gas is the least of your worries. But everyone has their own priorities. What the hey, a nine year old discussion is not the record.
Here is the scoop as far as I can tell for idle gas use per hour by vehicle type
Vehicle Type Fuel Type Engine Size
(liter) Gross Vehicle Weight
(GVW) (lbs) Idling Fuel Use
(Gal/hr with no load)
Compact Sedan Gas 2 - 0.16
Large Sedan Gas 4.6 - 0.39
Compact Sedan Diesel 2 - 0.17
Medium Heavy Truck Gas 5-7 19,700-26,000 0.84
Delivery Truck Diesel - 19,500 0.84
Tow Truck Diesel - 26,000 0.59
Medium Heavy Truck Diesel 6-10 23,000-33,000 0.44
Transit Bus Diesel - 30,000 0.97
Combination Truck Diesel - 32,000 0.49
Bucket Truck Diesel - 37,000 0.90
Tractor-Semitrailer Diesel - 80,000 0.64
Source: Argonne National Laboratory, Idling Reduction Savings Calculator, accessed December 2014.
Using the .39 gallons per hour at 20 3 minute stoplites .39 gallons used at $3 per gallon You will save $1.17 per hour of idle.Now the starter for my car alone was $200, so the 200 dollars for the starter is 170 hours of engine off at idle. Multiply by 20 for the number of starts so that would be an extra 510 starts by starter motor to break even. Not worth it in my book.
The Geo Metro I owned would change idle speed slightly when I turned the headlights on or off as the increased current draw on the alternator loaded the engine, so itās not like your carās electricity is free.
I have also seen this on some of the motorcycles I have owned, turn on the headlights, and the engine idle speed dropped a little.
Iām tempted to put LED headlights on my bike just to see if my gas mileage goes up slightly, or at least free up some alternator capacity to power heated clothes in the winter months.
Why would you reply to someone who has not been here since 2007?
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Well - I guess the topic had some interest to people - which is why people respond to an issue posted (by me) 10 years ago. Itās interesting that I now own a car that shuts off the car engine automatically when at a stop light. I own a 2016 mini cooper - manual shift. When I stop the car, put it into neutral, and lift my foot off the clutch, the engine stops. When I lift my foot off the clutch, the car starts.
This feature is now commonly found in many cars in Europe. Saves gas and reduces pollution. And if you think about it, it really does not add a significant amount of engine starts per day. I do mostly highway driving, so this feature may only be activated a couple of times per day.
One of the commenters attempted to compare the gas savings to the risk of reaching end of life of the starter sooner. Letās say the average car is started 6x per day or 2000 per year. The question to ask is: what is the expected mean time (or number of starts) to failure for a starter motor. If the mtf is 60000 starts, then over a ten year period you could double your starts and still not reach the average mtf - so the risk of starter motor failure due to excessive starts is relatively low. But if the mtf is low, then this would make a difference. Without this info, a conclusion cannot be reached.
But I find it interesting, that many car makers, particularly in Europe, have found that this is a feature that is worth adding to the car.
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My understanding is that when a manufacturer adds that feature, they beef up the starter system at the same time. There could also be a problem with the crank bearings, and they need improvement.
one link I found:
Here is some data for you. In my model year 1999 car, I rebuilt the starter at about 170K. Donāt know how many starts in 18 years, but it has been a mix of local and distance driving.
The rebuild used about $14 in parts.
And my imperfect memory says a remanufactured starter was from about $50-120, and a new one was from $120 upwards.
Can I expect the rebuild to last another 170K and 18 years? Donāt know, and Iām not going to concern myself with that.
As for more car makers using this feature, it could be all tied to emissions regulations and how emissions are tested. Car makers squeeze every little bit out to meet regulations, without concern over whether a starter goes 170K or not.
Thanks for the link. It would be interesting to ask car makers whether the new starters are already in new cars.
The new bearing material and oil sound a ways off.
Would you like ketchup with those words that you now get to eat?? (see reply#47)
I was behind a Volvo driving through downtown stop and go traffic the other day, and it must have restarted somewhere near 40 times in the 7 or so minutes it took us to get through the 3 lights I was behind him for. It seemed to shut off everytime the car stopped. it seemed excessive to me
I had a Jeep Rental car a couple years ago that would shut off after sitting idle for like 20 seconds (estimate- I donāt remember exact.) but would start immediately when you hit the throttle pedal.
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Very interesting discussion. I hadnāt given it a lot of thought but I like the idea of the car being made to shut off vs turning it on/off yourself. Built in efficiency for the win.
People with AT who inch forward every few seconds are going to do that. Iām pretty sure the start/stop is based on the brake pedal.
Sure. Fair enough.
You buyinā? 
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Sure, heāll buy when we finally start having regional Car Talk gatherings as was suggested a long time ago.
Of course, Iām so far away from everyone I doubt Iāll see any Car Talkers any time soon . . though Iāve tried . .by mentioning events that would be a good road trip like when the Great American Race comes down RT66.
I know thereās some Arizona members and Random Troll is in Albuquerque.
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The last starter I replaced or had replaced was in 1981. If you increase the usage by up to 1,000 percent I can see the fallacy of this theoretical discussion. I have only been rear ended once. October 2002. I had just stopped with brake lights on with at least 2 dozen other drivers. 2 thru and 1 left turn lane (3 red lights)! My headrest smacked me so hard I was unconscious for about 30 seconds. The first thing I remember post impact was the idiot tapping on my window with his cellphone!
Unfortunately it does not wake up all the idiots.
Your point is?
I have a simple solution to this topic. My 2010 Kia has an average MPG display I checked several times the old fashioned way and it is very accurate. I would say more accurate when fuel pumps shut off can vary. I agree shutting the engine off when stopped will save fuel. How much? I experimented today. Stationary idling produces the absolute worst mpg (zero) as no miles are driven. A cold start at 1500 RPM with stored information (21.0mpg) due to excessive ice clearing idling lost .1 mpg in 85 seconds. Of course this was not accurate. Idle speed was then normal 700 RPM. It then lost .1 mpg in 3 minutes 55 seconds. In my opinion shutting off the engine at stop lights is not worth worrying about.
+1
And, even though I am not claiming that this factor would come up often, just the chance that it could arise is a good reason to keep your engine running while at a stop light:
If you look in your mirror and see a vehicle approaching your stopped vehicle at high speed, having to start the engine before moving out of the way could have serious consequences.
Similarly, an oncoming vehicle that endangers you is something that you would be less likely to be able to avoid if you first have to start your engine and put the trans into gear.
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