[Llarry]

Automatic stop/start is one of the more unpopular features with car buyers, though I must admit it has never bothered me much. Multiple news outlets report that the U.S. federal government is exploring an end to the mandate that automakers incorporate this feature in new cars. That may be complicated by the mandates in other countries (EU, etc.)

[Chihuahua]

Have it on my DD, I turn it off every single time I drive the truck. I can't think of a better way to beat timing components and starter motors into premature death.

[W2k]

Auto start/stop has been around for long enough that there is very solid data on whether it causes premature wear and failure of starters and other components.

Short answer: No, it does not. It's an internet myth.

By one estimate (from Toyota, who are not exactly known for unreliable cars), you would need to replace the starter after 384,000 cycles. That's more than 21 starts/day for 50 years.

The purpose of the system is to save fuel, that is to say, your money. Again, there is solid data on this. Using it saves you 7.27-26.4% fuel (source).

Over the lifespan of the car, that's going to be thousands of dollars. Way more than what a new starter would cost, even if the system did destroy it prematurely, which it does not. Sounds like quite a lot of money to be leaving on the table to me.

[BroDoze]

It sucks and should be removed as a requirement. Make it an opt-in in the menus vs default on.

[Alfisti]

It's a horrible, horrible intrusion and creates dangerous lag when turning across traffic (left turns in USA/Canada). I am fine with it being there but there should be the ability to permanently turn it off if you choose, not every time you get in the car.

[NSXR]

Originally Posted by W2k

Auto start/stop has been around for long enough that there is very solid data on whether it causes premature wear and failure of starters and other components.

Short answer: No, it does not. It's an internet myth.

This is incorrect.

The increased wear is on the cylinder walls because of a momentary lack of oil (removed by the piston ring), and in combination with manufacturer's suggested (MIL) oil changes, which are 7,500 to 10,000, you'll have very shortened engine life expectancies (and we are already seeing that). In short, if you want your new Toyota engine to last 200K, you'll need to ignore the MIL and do 3K oil changes, and you'll still have premature wear.

Your only option is to disable the start/stop feature, burn a bit more gas, and keep the engine lubricated properly in the process.

[W2k]

@NSXR, not saying you're making this up, but could you provide a source or a study for this claim?

[NSXR]

Originally Posted by W2k

@NSXR, not saying you're making this up, but could you provide a source or a study for this claim?

It's not a claim, it's science.

The claim is that additional start/stops do not increase appreciable wear. Imagine Nike said something utterly stupid like additional steps do not increase appreciable wear on your shoes. It's ridiculous. Have a search on YouTube where these guys actually work on cars instead of read papers. You'll learn a lot more real-world facts from channels like I Do Cars than sales-driven manufacturer claims.

What you're missing is the scale they're using. It's not infinite like it used to be, it's "to an acceptable mileage."

Did you realize that BMW considers the service life of all their vehicles to be 186,000 miles? You have to dig to find it, but it's there. And additionally, they don't consider any owner beyond the first. This is why they can design a Hot-V without a care in the world.

All manufacturers do this to some degree, even the Gods Honda and Toyota. Their vehicles have a service life, and if wear on certain items is within that service life, even if it's significant, or increased by changes that will help them sell cars or meet emissions, it's acceptable. Engines fail, and if yours fails at 120K, then so be it, we are in the age of the throwaway car, right? But it didn't used to be this way, and there are clear reasons for the change.

[Mech Spec]

Lol.

As if the oil immediately disappears from the cylinder walls the second the engine shuts off. Every square centimeter of the inside of the engine is covered in oil and it doesnt disappear in 10 minutes nevermind 10-30 seconds.

It's not science because science is repeatable evidence backed study.

[afadeev]

Originally Posted by Llarry

Automatic stop/start is one of the more unpopular features with car buyers, though I must admit it has never bothered me much. Multiple news outlets report that the U.S. federal government is exploring an end to the mandate that automakers incorporate this feature in new cars.

Auto start/stop is NOT a mandate.
It's trick OEMs use to improve MPG ratings.

Originally Posted by Llarry

That may be complicated by the mandates in other countries (EU, etc.)

Fake news.

Originally Posted by BroDoze

It sucks and should be removed as a requirement. Make it an opt-in in the menus vs default on.

I don't really care all that much about auto-start/stop, but I do agree that more options should be configurable in the car and preserved through ignition starts.
This may be one of them, along with default M-mode ON at the start, cruise-control ON at the start, fake sounds in the cabin, etc. Some of those can be coded with E-sys, others not at all.

Originally Posted by NSXR

It's not a claim, it's science.

No sources == you made it up!



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[BlkGS]

I have not noticed any difference in fuel economy between having it on or off. I turn it off all the time because it's annoying, and it's hot here and I don't want my AC to turn off or fan to slow.

[Mech Spec]

Originally Posted by BlkGS

I have not noticed any difference in fuel economy between having it on or off. I turn it off all the time because it's annoying, and it's hot here and I don't want my AC to turn off or fan to slow.

You need the engine off for 7-9 seconds before you have saved any fuel. In my own usage, I started tracking how long the engine is off with start stop. For me it is only like 10-20% of the times start stop engages that it has the engine off for more than 9 seconds.

I find start stop annoying, and as noted above its not really saving fuel for me, so my car always starts in sport individual mode

[Humdizzle]

its fine. it may only save an individual a few dollars a year, but factor that by millions of people and it is a significant drop in pollution/wasted fuel.

i do agree its annoying and slow to re-engage on non hybrid motors. which can be a safety issue.

[DanG]

I like that in my BMW it stays off once I set it off. I never have to worry about it. Next time I start the car it will still be off.

[Mason Hatcher]

Originally Posted by Llarry

Automatic stop/start is one of the more unpopular features with car buyers, though I must admit it has never bothered me much. Multiple news outlets report that the U.S. federal government is exploring an end to the mandate that automakers incorporate this feature in new cars. That may be complicated by the mandates in other countries (EU, etc.)

Can you cite just one of those "multiple" news outlets?

[Mason Hatcher]

Originally Posted by NSXR

It's not a claim, it's science.

The claim is that additional start/stops do not increase appreciable wear. Imagine Nike said something utterly stupid like additional steps do not increase appreciable wear on your shoes. It's ridiculous. Have a search on YouTube where these guys actually work on cars instead of read papers. You'll learn a lot more real-world facts from channels like I Do Cars than sales-driven manufacturer claims.

What you're missing is the scale they're using. It's not infinite like it used to be, it's "to an acceptable mileage."

Did you realize that BMW considers the service life of all their vehicles to be 186,000 miles? You have to dig to find it, but it's there. And additionally, they don't consider any owner beyond the first. This is why they can design a Hot-V without a care in the world.

All manufacturers do this to some degree, even the Gods Honda and Toyota. Their vehicles have a service life, and if wear on certain items is within that service life, even if it's significant, or increased by changes that will help them sell cars or meet emissions, it's acceptable. Engines fail, and if yours fails at 120K, then so be it, we are in the age of the throwaway car, right? But it didn't used to be this way, and there are clear reasons for the change.

Lol. He didn't ask you to bloviate again, he asked for source for your claim.

[NSXR]

Originally Posted by Mech Spec

As if the oil immediately disappears from the cylinder walls the second the engine shuts off.

Originally Posted by afadeev

No sources == you made it up!

When the engine shuts off the oil is still on the cylinder walls. Unfortunately, upon every startup, be it 1 second later, or 5 hours later, the piston ring scrapes that oil off of the cylinder wall, causing wear. The more starts and stops, the more scrapes, the more wear.

Originally, part of the big pitch of synthetic oil was the fact that it stuck to the cylinder wall better, therefore reducing wear. And this is still true to this day, but more starts will always equal increased wear.

There are also some engines that have various fibers (FRM) or ceramic (CRM) made into the cylinder walls to help with wear, but the vast majority of engines do not have this technology because it causes other issues down the line, and is incredibly expensive.

Originally Posted by Mason Hatcher

Lol. He didn't ask you to bloviate again, he asked for source for your claim.

And I politely told him to research it for himself with the guys that fix engines, not the guys that sell them .

[spazzyfry123]

Having vehicles that had it, I seemingly got used to it relatively quickly. As someone mentioned, the crossing traffic thing introduces a certain level of panic when it doesn't kick on the way you anticipate. That was really my major gripe.

Another slight gripe would be the A/C, but it seems that it isn't too much longer after I start to notice the air temp rising the car does, too, and kicks it back on.

I currently don't own anything with the stop/start - I honestly forgot about it until this thread popped up

[Vindicator3]

I expected it to bother me more than it does. Very smooth on my 540 (a bit less smooth on my wife's Honda Pilot) and not enough lag to cause me any concern about a quick move. Comes on if the climate control needs it, even while stopped, so that's not an issue either.

I am concerned about other issues like starter burnout or other wear so interested in any large-scale (non-anectodal) data on whether it makes a difference. If it takes more than 200k miles to make a difference, I'm not sure it would bother me. If it's going to halve the life of my starter or (definitely) halve the life of my engine, I'd want to see the data/studies on that.

[Efthreeoh]

Originally Posted by NSXR

It's not a claim, it's science.

The claim is that additional start/stops do not increase appreciable wear. Imagine Nike said something utterly stupid like additional steps do not increase appreciable wear on your shoes. It's ridiculous. Have a search on YouTube where these guys actually work on cars instead of read papers. You'll learn a lot more real-world facts from channels like I Do Cars than sales-driven manufacturer claims.

What you're missing is the scale they're using. It's not infinite like it used to be, it's "to an acceptable mileage."

Did you realize that BMW considers the service life of all their vehicles to be 186,000 miles? You have to dig to find it, but it's there. And additionally, they don't consider any owner beyond the first. This is why they can design a Hot-V without a care in the world.

I'm pretty sure the 186,000 mile (300,000 km) milestone came from my initial reporting in 2013 of the E90 oil life monitor ceasing to calculate OCI after 300,000 km. I was the first E90 owner to discover the threshold existed through a diagnosis process at BMW of Sterling (Virginia). It's well documented here on E90 Post.

A decade ago, some car internet site took that thread and turned it into "BMW considers the life expectancy only to be 300,000 km." I assume based on a sarcastic remark I made in the thread on the subject. I went on that site and set the record straight.

The truth is I don't believe it and never have believed BMW thinks any of its models have a targeted lifespan of just 186,000 miles. My 35-year experience with BMW ownership has proven otherwise. I owned a 1989 E30 the reached 300,000 miles, I have a 1997 Z3 with 199,870 miles on it so far, and my 2006 E90 at 426,840 miles (as of yesterday). Further, if BMW actually set a life expectancy of just 186,000 miles, it would not keep parts in inventory for well over 20 years past the last build date of any of its models. As an example, my 27 year old Z3, which was a somewhat limited model sales volume wise, still has a majority of its parts available as new OE parts available from BMW.

Just wanted to set the record straight. The 186,000 mile life expectancy is internet myth.

[ZL9M2]

The start/stop function obviously causes more wear on the starter. Source = common sense. If it didn't then starters would last forever.

[NSXR]

Originally Posted by Efthreeoh

I'm pretty sure the 186,000 mile (300,000 km) milestone came from my initial reporting in 2013 of the E90 oil life monitor ceasing to calculate OCI after 300,000 km.

The 300,000 km number also apparently appears in BMW's own carbon ceramic brake literature. I have it in pdf somewhere, it was for the F10, and BMW was basically saying that for a street driven car the CCB's would never need to be replaced, "never" meaning they would last longer than the service life (300,000km/186,000 miles) of the vehicle.

Originally Posted by ZL9M2

The start/stop function obviously causes more wear on the starter. Source = common sense. If it didn't then starters would last forever.

I think it's relatively easy to make a starter motor last to 200K, but not so easy with cylinder walls.