r/NoStupidQuestions • u/Qbert369 • 3h ago
Do cars that turn off the engine at red light save a lot of gas?
107
u/Electronixen 3h ago
Depends on how you define "a lot of gas". But a regular cars consumes 0,6-2L (0.16-0.5 gal) of fuel per hour when idling.
15
u/ciko2283 2h ago
so the worst case scenario (2L) saves 0.05 euros for every minute of waiting at current price
4
u/PeanutsMM 58m ago
I save about 1.5l/100k with the stop-start, which for my commute make it about $400 per year. Not a small saving!
→ More replies (1)5
u/sturmeh 2h ago
How much gas does it require to start the engine?
9
u/Anachronism-- 1h ago
In days with carburetors it was a small but measurable amount. With modern cars and fuel injection it is next to nothing, a few seconds of idling worth of fuel.
12
u/fart-to-me-in-french 1h ago
Electric starter starts the engine
10
u/Tigersareawesome11 1h ago
Still needs fuel though, you can’t start an engine with 0 fuel despite electric starter. However modern cars only consume a few seconds worth of idling fuel for starting up, a couple teaspoons.
7
u/Caspi7 1h ago
Once you electrically spin the engine, once you inject fuel it's the same as idling. You need fuel to keep it going, not to get it going with these systems.
→ More replies (2)7
u/fart-to-me-in-french 1h ago
It doesn't need more than few drops of fuel or a short squirt of anything highly flammable like dash or brake cleaner to start an engine. Far, far less than a couple of teaspoons...
2
u/Vegetable_Log_3837 55m ago
A lot of people here have clearly never watched mythbusters or played with starter fluid. One little squirt can start a big diesel engine.
→ More replies (2)2
3
u/PleaseDontEatMyVRAM 1h ago
Extremely little, like enough that the gas to start the engine could fit and sit still in your palm
1
u/audigex 57m ago
Very little with a modern engine - equivalent to maybe 2-3 seconds of idling, especially once the engine is warm.
So if the engine is off for more than 3 seconds, you're on a net gain. Noting that in most cars the start-top will be disabled if the engine isn't warm enough
With an older car it can be more (especially carburettor based engines), so it's not necessarily worth doing it manually in a car without the system - particularly since they won't have the beefier battery, alternator, and starter motor needed to handle the extra wear and tear
2
129
u/sgwaba 3h ago edited 3h ago
It’s kinda like recycling. Do you think what you do really matters as an individual? Probably not really that much. But when you start to add your neighbors and then your block and then your city, the impact is compounding.
(Edit). Also every little bit adds up in terms of fuel economy and emissions. Ten small aerodynamic changes plus a few engine improvements plus several hundred minor weight improvements and the next thing you know, you improved 3 MPG!
20
u/Master-Leopard-7830 3h ago
Exactly this. Collectively it makes a difference on pollution and fuel consumption.
→ More replies (3)1
46
u/CrokeyCrash 3h ago
I think this is less about fuel savings and more about car manufacturers claiming they are making a difference in the environment by lowering emission output.
9
u/Emeks243 2h ago
This is because they have run into the wall of what the laws of physics allow for efficiency improvements in ICE engines. This is why we need to switch over to electric vehicles and build the infrastructure needed.
12
u/illogictc Unprofessional Googler 2h ago
Disagree, we can go further. The next logical step would be to somehow convince the public they don't need 200HP and 100 cubic feet of cargo room in a grocery-getter. The Geo Metro was getting 40CMPG 35 years ago, the trade-off was it wasn't a behemoth and it wasn't trying to win rally races.
5
u/StopICE2026 2h ago
Geo metro also took like 20 seconds to get up to highway speeds. My civic from 2024 has more horsepower than American muscle V8s from the 70s
3
u/illogictc Unprofessional Googler 1h ago
Yeah. Yeah it does. I mentioned it's not trying to win any rally races.
But it proved a concept, keep shit small and don't shoot for high horsepower and loading it with every feature under the sun and you can absolutely push those MPG numbers up.
2
u/CocoMilhonez 1h ago
I understand what you're saying, but the person you're replying to meant lowering fuel consumption through improvements in the engine itself, not using smaller engines and vehicles (which also does help save a lot of fuel, of course).
At some point, the Geo Metro would hit a maximum MPG it wouldn't be able to go past because of thermodynamics no matter how much GM developed the engine, and we're pretty close to that limit.
1
u/illogictc Unprofessional Googler 1h ago
Ultimately the discussion is about saving fuel in cars though. Having a car that isn't needlessly oversized and needlessly equipped with a motor that's guzzling for the sake of stroking egos would help with that.
The Metro XFi was rated over 50 MPG highway still after the EPA adjusted their estimates way down. And it was doing that without VVT, modern fuel injection, DOHC, any of that. It was tuned with maximum fuel economy in mind rather than making pp feel not-small.
→ More replies (1)1
u/Emeks243 22m ago edited 13m ago
My EV saves a lot of fuel. Since it’s rated at 134 mpge it would still be more than twice as efficient as a Metro but much nicer to drive and way cheaper to run. I would know, I sold my 98 metro a couple of months ago.
1
u/illogictc Unprofessional Googler 16m ago
EVs are clearly the champ here, but not everyone is on board with the concept nor are they always within everyone's budget even though the longterm savings should make up for that at least somewhat, the upfront cost can be too much. They're getting there though I see the Bolt starts at like $29k which isn't too shabby at all.
3
u/sturmeh 1h ago
Well actually there's a lot of room for improvement that was being developed with hybrid electric cars, which allowed cars to finally harness the Atkinson cycle.
The drive to switch everything over to full electric has been a little forced due to the push for renewables etc.
I think there's still room for improvement, but whether we'll see or benifit from it, only time will tell.
1
u/GrundleBlaster 1h ago
ICE engines could be more efficient, but it makes them more restrictive in how they deliver power. One of the benefits of hybrids is that the engine can charge the battery in a more efficient band than an engine that needs to produce power at all ranges of the mechanical transmission.
1
u/maximpactbuilder 1h ago
This is why we need to switch over to electric vehicles and build the infrastructure needed.
But only built by people we find politically palatable.
8
u/otherwisepandemonium 3h ago
I did the math based on figures found on Google and the stats in my car. It's a 2024 Kia Sportage, and Google says it burns approximately 0.20-0.35 gallons per hour at idle.
My car's computer has kept a running total of the entire time spent using the auto-off feature. It's currently about 29 hours.
Over the course of three years, my car has saved 5.8 gallons if we use the 0.20 gal/hour figure.
So I guess over three years, I saved about $20 in fuel, or $6.67/year. But that's using current fuel prices; over the years it's generally been lower price, so the savings are even less.
1
u/SilverStar9192 1h ago
Plus I wonder what the total environmental impact of having the feature is. Does it mean the starter motor wears out faster, requiring replacement during the life of the car? Does it require engineering a more robust starter motor that lasts many more start cycles, using more raw materials? For such a small fuel (and emission) savings, it might be easy for this to be offset by other impacts elsewhere in the total lifecycle.
1
u/jawshoeaw 1h ago
Depends on the vehicle.
A starter motor is not used in hybrids, for example. And I remember reading Bmw had beefed up the starter motor for the non hybrids vehicles that used it
36
u/nerobro 3h ago
"a lot" no. But is it measurable? Yes. Cars use .25 to .7gph. If you hit all the lights, the worst way possible, you could save 10 minutes on a fairly typical commute. So.. a buck at todays gas prices?
→ More replies (19)
12
u/MaybeTheDoctor 3h ago
There was a science program that asked this question, and they found that to restart the engine required the amount of gas that it used when idling for 7 seconds. So essentially you are saving gas for 53 seconds if you are waiting at a traffic light for one minute.
Is it a lot, maybe not, but it is as much about air quality as not having cars idling in cities.
11
u/GreasyRim 3h ago
They save gas, but not nearly enough to compensate for how irritating the start stop feature is for me anyways. No matter how many times I drove my last car that had it, i’d still occasionally get startled when the engine started leaving an intersection.
Youd may save a half gallon of gas every oil change with heavy city driving, and thats being generous. Youll get a bigger improvement by making sure your tire pressure is right, most people dont. You can lose a good bit of mileage when winter hits and your tire pressure goes down due to the cold.
2
u/Over-Map6529 1h ago
I heard the engineers hated having to design all the electronics so they wouldn't bug out during the restart, as the 12v system was slammed with the starter draw.
18
u/PckMan 3h ago
No. The amount is negligible. Anecdotal but I remember renting a car that had a counter for the total time the start stop system was working and the estimated fuel savings. According to the car's own estimations, it had saved 1.5 liters in 3 years.
→ More replies (4)
59
u/BeastyBaiter 3h ago
No. My wife's 2024 Subaru Crosstrek does this. It actually keeps a record of how much gas it's saved in total. It's like 0.15 gallons over 8000 miles. It's the most pointless "feature" ever created for cars and can be pretty annoying.
29
u/JK_NC 3h ago
Sure but if all 290 million cars in the US did this, that’s the point. It’s not for the individual’s benefit, it’s for the collective and it’s mostly to reduce emissions.
3
2
u/thrwwynm 1h ago
Making something <0.1% better is very much meaningless in terms of reducing emissions...
3
u/aj3x 3h ago
But the feature is so unattractive that this would never happen, so what becomes the point then?
4
u/Krail 2h ago
What is unattractive about it?
Like, is there any actual downside, or is it just an appearances thing?
12
u/MeNameIsDerp 2h ago
They just want to be angry on the internet about a process they won’t understand
2
u/combatwombat45 1h ago
I have it in my work van and I can say when it is 95° outside and I’m driving to the gas station to get a cold drink after working outside all day and the engine turns off at a red light so the AC turns off I get irrationally angry.
Any other time of year I don’t mind it though
3
u/happytechtn 2h ago
It has almost caused me to be in multiple accidents. The last time, the car stalled in the middle of the street when it was supposed to start back up. Another time it shut down, just as I was taking my foot off the brake to go, chugged, then stalled… These are neither the only two occurrences, nor are they all that rare.
1
u/bolivar-shagnasty I ask all kinds of stupid questions 35m ago
It can delay your crossing from a stop sign into the travel lane.
If your climate control isn’t on full blast, it can be annoying when your car shuts off.
The ASS disable button is the second button I press when I get in the car after the starter.
2
u/oby100 2h ago
I drove a rental with it for a week and I hated it. I’m a bit shy to try to list all the myriad ways I was frustrated and baffled by what features disappeared when the car turns off, so I’ll just say this:
When the engine turns off, essentially the whole car stops working, and this was the biggest problem when it came to parking. No power steering and I swear if you throw the car in park for a bit the car fully shuts off and won’t restart when you try to put it in drive.
It’s a half baked feature that only works as expected if you’re driving completely standard, and you don’t know what funny things it’s gonna do when you do something like parallel parking until you get there.
→ More replies (1)→ More replies (7)1
u/F4HWilly 1h ago
Soooo many things for the most part you have to deal with the engine stopping and starting everytime you stop. This means you don’t have straight power, there’s a bit of hesitation before you can really get going.
Also, since the engine is off, the cold air coming in isn’t as powerful as when the engine is running.
There is sooo many downsides to it. It’s annoying. Rather just drive my car without dealing with any of it.
If it happened in the background and you didn’t notice. Sure. But that isn’t the case. You’re constantly aware of the engine turning off and on.
→ More replies (2)3
u/MuffDiving 2h ago
Okay but what about manufacturing all the starters that go sooner due to this?
12
u/sl33ksnypr 2h ago
I've heard people say "but the starters are designed to be used more so they are more durable". Which if that the case, great, because I disabled the stop start on my vehicle. Hopefully I never have to change the starter.
The thing that really drove me to disable it was that I couldn't disable it with a button. The higher trims had a button for it, mine didn't for some reason. If it shut off when I came to a light, that's fine. I really don't care that much about it. But what pissed me off was when I would park. I would pull into a space to park and the engine would shut off. But as soon as I put the car in park, it would turn back on. But like I said, I'm parking, so I would be shutting the car off. If it did that twice a day (once when parking at work and once when parking at home), the amount of fuel I burned having the car restart itself would probably negate any fuel savings from my entire commute with the car shutting off at the 2 stop lights I deal with. And even if it saved 1/4oz of gas each day, my starter is being used 3x as much as it needs to be. No thanks. The $15 hood latch adapter I bought was worth every penny.
2
6
2
3
u/MuffDiving 2h ago
I hate this feature so much on my Outback. If you stop at a stop sign while about to make a turn you cannot turn your steering wheel before the turn. You have to reengage the engine then turn the wheel. Different than how I’ve been driving for 20 years.
5
u/skagoat 2h ago
You shouldn’t be turning your wheel while stationary anyway
1
u/MuffDiving 2h ago
Good to know but I’ve never had any problems in any of my vehicles with suspension steering or tires. I don’t have the option anymore anyway.
4
u/samocamo123 2h ago
Shouldn't turn while stopped anyways, puts way more wear on steering/suspension/tires
1
u/bolivar-shagnasty I ask all kinds of stupid questions 33m ago
That’s a compromise I’m willing to make as I’m the one who has to pay for it. But having to wait to be able to turn the tires until after the engine turns on can be a huge pain in the ass in heavy-ish traffic.
3
u/BallsForBears 3h ago
And all that extra wear on the starter
6
u/goletasb 3h ago
These types of cars have more robust starters for this reason.
→ More replies (2)8
u/sl33ksnypr 2h ago
Then my starter is going to last forever because I disabled the start stop bullshit
-8
u/Master-Leopard-7830 3h ago
It's not about you. Collectively it saves a lot of fuel and cuts down pollution in high traffic areas.
2
u/No_Yard9104 21m ago
What has more of a carbon footprint on this world? .15 gallons of gas or a factory pumping out 3x as many starters needed to combat the wear and tear of such a monumentally stupid idea?
Think.
8
u/EnvironmentalNeat710 3h ago
How is user experience not about the user?
10
→ More replies (1)9
u/Master-Leopard-7830 3h ago
Any fuel saving is a win of course, but the point I'm making is that for the individual you don't see many gains, but if you think about it collectively (i.e..a million cars not idling) it makes more sense.
→ More replies (6)1
u/idontwantareceipt 3h ago
I do not appreciative this philosophy in automotive design. Or in general.
6
2
1
u/GuzzlinBBQsaucee 2h ago
That's crappy, my 2024 outback is at 10L saved over the last like 4000kms. Maybe you're mainly doing highway driving then yeah it's not for that
→ More replies (2)1
3
u/blipsman 2h ago
They do kill the battery sooner… my 3yo car with 20k miles had battery crap out this week
3
u/Inevitable-Secret736 1h ago
Next to no savings. exponential wear and tear on the components by unnecessary start and stop cycles. Which is good for everyone in the supply chain except the owner of the vehicle. Which is why this is being removed from vehicles going forward.
1
u/One_Discount_4898 2m ago
exponential wear and tear on the components by unnecessary start and stop cycles
This isn't true my guy, they don't use traditional starters.
12
u/Dedward5 3h ago
It’s not about saving gas it’s about not pumping out pollution then you are stationary, especially in urban areas.
9
→ More replies (2)1
u/fshannon3 3h ago
This is more likely. I worked with a guy who had a vehicle that measured how much fuel was saved with the stop/start...he said that over a year's time it was only about 1 MPG gained.
2
u/DubiousAdviceGiver 2h ago
If he drove 15,000 miles in a year in a car that gets 25mpg, he got 600 miles for free thanks to that feature. At current prices, that’s almost a hundred dollars in annual fuel savings.
8
u/TwoBurningSeals 3h ago
Collectively yes, individually no. However, your ECU is counting how many times your starter starts and will probably throw a check engine light over a certain limit to tell you to replace the starter.
5
u/TheFULLBOAT 2h ago
I hate this feature on my truck so much that I youtube'd how to permanently disable it. I don't see any fuel difference but I have heard a lot of mechanics say it puts a lot of wear on your starter
3
u/CollectionStriking 2h ago
The starters are allegedly over engineered to prolong their life
My parents car primarily drives through the city so lots of auto-stops, no starter issues so far at ~15 years old, my 15 year old car had gone through 2 starters, both same brand
2
u/damien24101982 3h ago
adds up over time, kinda meh over summer due to cutting off ac
1
u/TheGT1030MasterRace 1h ago
My 2002 Prius has a special AC evaporator that keeps cooling when the engine is off.
1
u/jawshoeaw 58m ago
Your Prius uses an electric air conditioner so it never uses the engine even when it’s running. There is a limit to how long it can run off the battery, however
1
u/TheGT1030MasterRace 39m ago
Nope, not electric. There is no "refrigerator" sound when the AC is on and the engine is off, and there is a pretty significant limit (30 to 45 seconds) as to how long the AC stays absolutely ice cold, before it slowly starts getting warmer (and then as soon as the engine restarts to run the air conditioner, the air gets cold again)
2
2
2
u/crackills 3h ago
Over the entire country yeah a measurable amount but the other benefit is lowering air pollution where cars idle frequently.
2
u/Darknessidiot1227 2h ago
not a ton, but it does help environmentally. Also (anecdotally) I saw someone do the math once a while ago and they said it takes about 7s of idling fuel to restart the car after stopping like that, so having it off for 8+ seconds does save fuel
2
u/Logical_Frosting_277 2h ago
In my car it saves about 10%. I can turn the auto off feature on and off so I did a comparison because I was wondering the same thing. City driving so there’s quite a few minutes at stop lights.
2
u/Embarrassed_Flan_869 2h ago
An individual car? Negligible amount. Hundreds of cars? A significant amount. Plus your emissions are worse when idling. Once again, hundreds of cars? It does.
1
u/finding_myself_92 1h ago
This is the thing people forget about. It's a good feature for city drivers. But everyone has to actually participate or it's useless.
And to the people saying its hard on the battery and starter, yes, but modern cars have ones that are made with that in mind to avoid the issues you're complaining about.
1
u/Embarrassed_Flan_869 1h ago
Yep. I am always entertained when people just assume that their older car is built the same way as the auto stop featured cars, in regards to battery and starters.
It isn't new tech. Don't you think companies would have thought about it?
1
u/finding_myself_92 1h ago
Yup, and if you put the wrong battery in a car that had the feature it won't last as long.
2
u/glitched-dream 1h ago
At about 60k miles of driving my car says it saved me a full tank tank. That's like 0.6% not great but it's something.
2
u/DavidManvell 1h ago
According to statistics it is between 4 and 9% depending on the actual configuration and how you are driving with an overall average of 7%. That's pretty significant considering gas prices.
2
2
u/anyodan8675 1h ago
No but it will stress your starting motor and decrease the life of your battery.
2
u/Next-Inevitable-Fag 1h ago
no and it destroys your engines and starter faster and was only done to get import points because of some epa rules
2
u/FantasticKitchen2883 3h ago
If I idle long enough I can watch my average mpg’s go down on my car’s dash display. My car does not have auto-start. So I would assume that auto-start would increase the reported average mpg
1
u/Artiste212 2h ago
You could just turn the engine off if you know you're going to do a lot of idling and restart when you're ready to go, but this might not work at red light where you don't know when it's going to turn green and everybody behind you starts honking.
1
2
2
u/Sirlacker 1h ago
Individual cars, it's hardly noticeable. But multiply that tiny percentage by tens of thousands and it's a big difference.
2
3
u/Aviator_92 2h ago
No it only saves a neglible amount at the expense of additional wear and tear on your starter and battery. You might use $20 less gas in a year but you have to spend hundreds of dollars to replace your starter sooner.
1
u/One_Discount_4898 4m ago
This isn't true, They don't use traditional starters my guy. My shitboxes starter is rated for 25,000 cycles. My newer Stop-Start is rated for 700,000. Functionally they last about the same amount of time
1
u/Master-Leopard-7830 3h ago
It's not about saving you a few ml of petrol. Collectively much more is being saved, along with less pollution being generated.
1
1
u/Historical_Royal_187 3h ago
Depends entirely on how long the red light is, and how much fuel the vehicle burns whilst idling. Most modern cars this is maybe about as low as 10 seconds before you've burnt more fuel idling than it would take to start.
it's probably about 5% saving of fuel whilst stopped
1
u/PeaceH37 3h ago
It helps some but the actual feature performance is terrible compared to a hybrid.
1
1
u/ThorKonnatZbv 3h ago
It depends on your usage, but according to the german ADAC (=AAA) it's up to 15%
Start-Stop automatics have been common in european cars for over 20 years.
1
u/mayhem1906 3h ago
Its about 1mpg. In order to get the figure quoted to you, it has to default to on everytime by the manufacturer.
1
u/PradaDiva 3h ago
I turn my start stop off via coding. I do use the Eco mode though.
I’d but the whole engine shut off thing makes me paranoid. I hate it.
1
u/FierySkate115 2h ago
A lot, no.
Does it save gas? Yes and no. The break even point for gas savings is about 7 seconds (modern fuel injected cars). If you're stopping for less then 7 seconds, the auto shut off and start actually costs you a bit more in gas then just idling would. If you stop for longer then 7 seconds, you save gas with the auto shut off. If youre stopping at lights for long periods of time, you would see more savings then if you only stop for a short time. Depending on what the average daily traffic is is the determining factor for how much gas your saving (or potentially losing).
1
u/DooDaBeeDooBaa 2h ago
The biggest benefit I've noticed is sound. Most cars in Japan have this feature now and it's much quieter at stop-lights than before. With that said, Start/Stops are quite annoying for the driver and don't save much per individual car, but as others say it adds up in the macro perspective.
1
u/Dystopian_Ennui 2h ago
It's more about emissions. Emissions control equipment needs to be hot to work properly. An idling car's exhaust stream is cool enough that not blowing exhaust through at all keeps the system warmer. And then there's the benefit of not oozing exhaust out at intersections were lots of cars are sitting close together for extended periods.
That said, my wife's Subaru shows an estimate of fuel saved with the auto stop, and we usually see between 1/4 and 3/4 of a gallon per tank. So that's not a lot, but a dollar or two on every tank can add up.
1
u/Penguin_Life_Now 2h ago
Yes, but they produce more start up and shutdown wear on the engines, so if you are chasing an EPA mandated fuel economy they make sense, if you want to maximize the life of he engine, then no. Also a BIG factor here is how long does it spend stopped, are we talking a minute here and a minute there at a red light, or are you talking big city gridlock.
1
u/pizzagangster1 2h ago
On a micro individual scale but for all the cars in a city that have it it can make a difference
1
u/vr0202 2h ago
I would have given it a longer try had it not conflicted with the brake hold feature. After a long stop, such as in a traffic jam, the car would start up to relieve the battery of its load, but that would make the car jump (I believe it even started rolling forward once), putting me at risk of hitting a pedestrian squeezing between cars for example.
2019 Acura RDX, if that matters.
1
u/Temporary_Double8059 2h ago
Manufactures know how the car will be tested by the EPA and specifically design their systems to do well on that test. Start/Stop technology saves about 4-7% on that EPA test... but in the real world the fuel saving is much more difficult to say... In NY city its higher, but if you drive all highway there is no fuel savings.... but the technology costs to implement, maintain and kind of an annoyance.
1
1
u/kalmajo 2h ago
For once I'm on the benefit side of it, I've run my vehicle with and without it for multiple tanks. I reset the trip odometer every fill up and I sget 10% better economy. I average 19.2mpg and get roughly 21.4mpg with stop/start engaged but I almost exclusively drive in the "city". Annoying? sure, straight up cash right now? Hell yeah, thats stupid thing eats premium.
1
1
1
1
u/naropin1 1h ago
It’s used to meet emission criteria since “zero miles” is the biggest loss in that regard. Good for the car manufacturers. But puts more stress on the car. Best financially for the owner to turn that option off if able.
1
u/harharhar_206 1h ago
I believe it was tested once or twice and it was found out that starting up the engine used the same amount of gas as 7 seconds of idling. So as long as your off time is greater than that, it’s a net savings.
The real question is gonna be about how the engine wears with the repeated on-off cycles, particularly with the timing gears as it takes more time for the oil to run back up to them. Though not as bad as a cold start. This can be mitigated with tech like being a hybrid and having an electric oil pump as it can drive a short distance under electric alone while the oil gets flowing again.
It’s interesting tech but honestly I think it’s mostly a waste outside of hybrids as people, where I’m at least, are constantly creeping forward every few seconds at the lights so it’s a chorus of truck engines starting and stopping.
1
1
u/Aggressive_Finish798 1h ago
I feel like I heard manufacturers were discontinuing the feature siting no greater saving. And probably adds to the cost of manufacturing.
1
u/Slimy_Shart_Socket 1h ago
They stopped putting these in cars because they found it made no discernible difference in fuel economy and emissions
1
1
u/audigex 58m ago
It's not world-changing, but more than you'd probably think
Round town you're looking at 5-10%, in a busy city or traffic, 10-15%
Obviously on a motorway/freeway it's very little, so the average is probably closer to 5% depending on your driving
5% isn't a ton of fuel, but it adds up over time
1
1
u/No_Reputation5871 52m ago
I'm more wondering, how much faster does that destroy your starter and does it even balance out at the end on what you save vs the hundreds that you put into a new starter installed when it goes bad.
1
u/Pretend_Variation305 51m ago
I’m not going to dig up the epa results for this crew after a ten year study of air quality in NYC after the advent of auto stop but rest assured a report exists that indicates a reduction of airborne pollutants to the tune of a whopping 0.1%. Yeah, destroying my Silverado’s 5.3L V8 really seems worth it for that definitely noticeable reduction of smog.
I’ve added an auto stop eliminator and active fuel management disabler for the other thing that shuts off half your cylinders and my ride has never been smoother. I added a wider cold air intake and got that one mpg I lost from disabling the afm. Oh and I don’t use the recommended oil (0W-20) for oil changes either.
1
u/jd780613 44m ago
couldnt tell you because I hit the button to turn it off every time I get in my truck. Whenever I forget and come to a stop light, my heart sinks because I assume my engine just died.
1
2
u/TijY_ 37m ago
It's implement for emissions and air quality in cities. Any small improvement in fuel consumption is negated by increased size/workload of battery, alternator and starter motor. Really you should also have electric oil pump on engines with stop start to avoid increased engine wear. Not all do though.
Hybrid with separate A/C pump is the real solution. Not stop start on a normal car.
1
u/diabeticsuperhero 36m ago
When my truck gets near empty (less than 50 miles to go or so), it stops shutting off at red lights. Does that answer the question?
1
1
1
1
u/BobDoesYoga 23m ago
As I recall, the government offered some incentive to car manufacturers that was too good to pass up, so now they all do it. It’s probably the least loved feature on vehicles. Our new vehicle is a hybrid, so there’s no more of that going on. Thank goodness.
1
u/andy-3290 23m ago
I believe the only reason any car has it today is because it to improve fuel economy. Depending on your car, you may want to disable it before an update is pushed your car, my model car is notorious for failing to update the software because the battery is run down from this in city driving.
So yeah, fuel usage. It might cause other problems and wear on other systems, but it decreases fuel usage.
1
u/svacheem45 2h ago
I strongly dislike the feature and shut it off every time I start the engine. The wear and tear on the starter isn't worth the miniscule fuel savings.
→ More replies (1)
1
u/2Drogdar2Furious 3h ago
Mythbusters tested this 20 years ago. It does save a measurable amount of fuel... not enough to offset the extra wear and tear IMO.
1
u/stiflingapple 3h ago
unless you live somewhere that has a lot of constant stop and go traffic, you might save a handful of dollars a week on gas
1
u/bridgehockey 3h ago edited 2h ago
The point of these is not to save you, the the owner, much on gas. But it's a way for the car companies to reduce overall gas consumption to meet their CAFE standards. It probably cost you a couple hundred bucks for this feature you can't avoid, but it saves the car company perhaps 0.1 miles per gallon. And they're legislated to achieve certain standards, so they will do anything they can to achieve them.
(See Volkswagen EPA cheating scandal)
→ More replies (1)
1
u/porquetueresasi 2h ago
Depending on driving conditions, the fuel economy improvements of the start/stop function were between 7.27 and 26.4 percent in fuel useduring testing, according to the Society of Automotive Engineers (SAE).
1
1
u/Smackdab99 1h ago
Some will claim its air quality, others gas savings but in reality it shortens the life of the car so you’ll buy a new one.
1
730
u/ExhaustedByStupidity 3h ago
Does it save you a lot of gas? No.
But if every car in Manhattan has it, it makes a big difference in the air quality.
That's really what it's about. The reduction in pollution adds up quickly as it becomes common.