[ExZHP]

I am sure this topic has been discussed before, even though I can't find any recent threads. I wonder what the experts on this forum think about using this feature with the N20 engine (which, as I have been told, was designed with it in mind). What are pros and cons? Any metrics on long term fuel economy?

Personally, I keep switching it on and off. I don't like it in the city, where stops are usually brief, but in the suburbia, where sometimes you wait 30 seconds and more for the green, I like to turn it on. Should I be concerned with the starter and/or battery wear and tear?

[amw896]

I don't like it or use it. I believe the only time when gas consumption savings would offset the restart consumption is if you are idling for at least 2min. also, this system is torture on your starter and hot turbos.

[Sportstick]

Originally Posted by ExZHP

I am sure this topic has been discussed before, even though I can't find any recent threads. I wonder what the experts on this forum think about using this feature with the N20 engine (which, as I have been told, was designed with it in mind). What are pros and cons? Any metrics on long term fuel economy?

Personally, I keep switching it on and off. I don't like it in the city, where stops are usually brief, but in the suburbia, where sometimes you wait 30 seconds and more for the green, I like to turn it on. Should I be concerned with the starter and/or battery wear and tear?

I turned it off for my N20 on Day 1 after a few experimental tries, and it remains so. To whatever degree BMW enhanced the robustness of the starter and batteries to account for ASS, to the degree you don't use ASS, those components are stressed less and should have a longer lifetime. I know of no data on actual mean times to failure of those components with vs without ASS in use over a prolonged period, but find the logic compelling.

ASS is also quite unrefined and, to me, an annoying experience with each restart. The relative savings versus the real and potential negatives do not justify its use to me.

[3.0L]

I don't care for it, so don't use it. Ever. I'm glad there's a button there to defeat it.

[sausagemcmuffin]

Mine keeps randomly switching itself on... very annoying.

[ianp622]

Originally Posted by amw896

I don't like it or use it. I believe the only time when gas consumption savings would offset the restart consumption is if you are idling for at least 2min. also, this system is torture on your starter and hot turbos.

1. It's about 2 seconds, not 2 minutes. You can see your MPG ticking down as you are stopped with the engine idling.

2. It's not torture on the starter - the starter is brushless, so it can take the extra load. For example, the Prius is one of the most reliable cars and that has more start/stop cycles than any non-hybrid.

3. It's not torture on the turbos, there's an electric water pump for keeping them cool even when the engine is off.

I use it when I'm around stop lights, and disable it around stop signs.

[amw896]

I've never seen the mpg move when at idle. Only time I seen the blue mpg marker increase is when I'm in Eco mode trying to drive it like my wife's ct.

We have a ct200 and I doubt it's close to the same for the starter. This motor is designed to engage/disengage way more frequently than just at idle. That said, we are 90k on it and when it re engages, the jerk has definitely become more pronounced over time. Just wear and tear or is the starter on its way out? Only time will tell I guess.

I was not aware that the turbo had water cooling lines though. Thanks for the info!

[Ceejay18]

I never use it, I hate this feature on my MT 235i

[B_Rice]

I don't use it since it sounds stupid when your car has a loud exhaust.

[ExZHP]

Originally Posted by B_Rice

I don't use it since it sounds stupid when your car has a loud exhaust.

Lol, I guess I'm one of the few people on this forum for whom the exhaust sound is a low priority. Although I loved it on my old ZHP.

[breezygirl]

I turned it off as well.

[morphomeman]

I tried to like it but gave up in the end. Does anyone have any solid information on the fuel savings?

[3rdcoast228i]

I've only used it a few times and it does make a difference in mpg.

Who knows the long term wear it may cause... it could be negligible, depending on how long you really plan to keep the car.

Personally I think it's added stress that's not worth it. But I also plan on keeping my car about 10 years.

One of the thoughts is the timing chain and oil pump chain is being pulled on every time you start...

[rightrudder]

I like the fact that when you defeat it, the car doesn't automatically re-enable it the next time you drive the car. Now, if only I could have it default to Sport + instead of reverting to Comfort all the time! (Minor quibble with a fantastic car)

[bimmerfile]

Mine was delivered with start-stop programmed OFF as the default.
Never had the desire or inclination to activate it.
It's primarily a gimmick for manufacturers to meet increasingly stringent emissions and to look eco-friendly.

[DF]

I keep it off

[wdc330i]

Never use it. And so thankful it will stay disabled when you turn it off. With the Boxster, you have to shut if off each time you start the car.

[allthatisntnow]

Used carly for BMW to code it to be default off. Never bothered me, just never encounter a situation where it would genuinely save fuel.

[Y0tsuya]

I keep it on. Works well with my MT 235i.

On the AT 340i I turn it off as it prevents smooth braking.

[AbuQutaita]

I kept mine on. Maybe I'm one of the few who even wished there was a way to keep it on while in Sport mode...

[Kolyan2k]

Originally Posted by ianp622

1. It's about 2 seconds, not 2 minutes. You can see your MPG ticking down as you are stopped with the engine idling.

2. It's not torture on the starter - the starter is brushless, so it can take the extra load. For example, the Prius is one of the most reliable cars and that has more start/stop cycles than any non-hybrid.

3. It's not torture on the turbos, there's an electric water pump for keeping them cool even when the engine is off.

I use it when I'm around stop lights, and disable it around stop signs.

Doesn't it say in the manual that it shortens life of certain parts under the hood?

[RacerDad]

I use mine. We have had two hybrids so I am used to the engine shutting off at a stop. With temperatures in the mid 90s this week, the engine doesn't stay off long. I shut that feature off in those situations. I always shut it off in stop and go traffic because it is really not necessary.