[grooveK]

So i am a new owner of a 2024 m240i. i was driving on the west side highway today in manhattan, and for those that know, there's basically a traffic light every couple city blocks, four/five lanes each way. so im driving in comfort mode with ASS engaged and im stopped first in my lane at a red light. engine shuts off, everything normal. then the engine starts back up without me lifting off the brake (not sure at this point) and the light turns green half a second later. im not sure if i anticipated the green and lightly lifted off the brake but then i get stopped at another light a few lights later and this time, i make sure i dont make any movements and the car does the exact same thing. i tried this at one other light and it did the same thing. when i was at a red light and not the first car in the lane, nothing unusual happened and the engine started back up when i lifted off the brake.

so my question... am i going crazy? i did a quick google search and there were some old articles about audi researching this kind of tech but nothing specific to bmw.

any thoughts?

[eleven11]

If I'm understanding your concern/question correctly, you are perplexed that the car started without lifting off of the brake? If you are using energy when the vehicle is "off" (e.g. stereo, A/C, etc.), it eventually needs to restart the vehicle, even if you you didn't let off of the brake. It is variable depending on various factors - how long you have been driving, the temperature, etc.

[grooveK]

sorry, i think my confusion made it more difficult to articulate. my question/concern was the engine would restart by itself a split second before the light turned green three straight times when i was right infront of the traffic light... so im wondering if there is some sensor or technology in the traffic lights emit and the car can read it. or if im just bat-shit crazy. or all of the above.

Originally Posted by eleven11

If I'm understanding your concern/question correctly, you are perplexed that the car started without lifting off of the brake? If you are using energy when the vehicle is "off" (e.g. stereo, A/C, etc.), it eventually needs to restart the vehicle, even if you you didn't let off of the brake. It is variable depending on various factors - how long you have been driving, the temperature, etc.

[PL4NCK]

Originally Posted by grooveK

so im wondering if there is some sensor or technology in the traffic lights emit and the car can read it. or if im just bat-shit crazy. or all of the above.

While that is technically possible there is no communication between the traffic light system and your cars auto stop/start functionality. I suspect that it was just pure coincidence. As the previous poster mentioned, sometimes the computer will decide to restart the engine if you're using things that drain the battery, such AC, stereo, heated seats etc.

This video goes into some depth about it:

That link starts at the time where he explains the computer's logic for deciding to re-start at a traffic light. In short though, he never mentions any coordination between the traffic light system and the car itself.

[bobkat09]

Sounds like a lot of technology for a feature that I hate and never use

[J-RO]

You can turn it off after you start your car or put it into sport mode.

[KevinC]

Disable that crap. Permanently. Your battery and engine will last longer too.

[Littlecoupe]

I am not aware of BMW using any predictive technology for the ASS (what a wonderful acronym). I know mine does not start based on the light condition, for as little as I have used it. I think you had a very coincidental series of events.

[PL4NCK]

Originally Posted by bobkat09

Sounds like a lot of technology for a feature that I hate and never use

It is indeed an awful lot of extra tech and changes needed in order to support something so pointless.

[grooveK]

yeah i guess it has to be a series of coincidences.

im aware of most on this forum not being a fan of ass, but i want to try it out before i decide if i like it or not. im leaning not, but i want to give it a good run. just like trying to drive it in eco mode (feels like im driving with the parking brake on).

[J-RO]

BMW and Eco mode sounds like an oxymoron to me.

[danallxt]

Originally Posted by J-RO

You can turn it off after you start your car or put it into sport mode.

Actually you can turn it off BEFORE you start the car, that's my method, i don't hit the start button till i deactivate that and see the amber light. It's become a habit that is automatic.

[German1967]

I always shut ASS off - always!

[PNTDG42]

I use ASS from time to time. Usually I’m in sport mode though. Don’t be upset it’s there even if you don’t like it… it’s a relatively expensive vehicle and leaving out features that cheaper cars have is not a good look (even if some of you don’t/won’t use it).

[BlueLEDz]

I use the ASS when I’m at a long light but other wise keep it off. Have found that driving in eco has such a delay in thrust that I end up applying too much force to the pedal and more gas is used then required.

My gas mileage was worse in city driving with eco mode on vs sport individual with everything set to comfort.

Cruising on the Highway eco mode and ASS are work great. But not for stop and go traffic.

[Pentland]

I don’t get the hate for Auto SS. Just let it do its thing.
It kicks in quickly, never a hinderance.

[Evilmoretea]

Originally Posted by grooveK

So i am a new owner of a 2024 m240i. i was driving on the west side highway today in manhattan, and for those that know, there's basically a traffic light every couple city blocks, four/five lanes each way. so im driving in comfort mode with ASS engaged and im stopped first in my lane at a red light. engine shuts off, everything normal. then the engine starts back up without me lifting off the brake (not sure at this point) and the light turns green half a second later. im not sure if i anticipated the green and lightly lifted off the brake but then i get stopped at another light a few lights later and this time, i make sure i dont make any movements and the car does the exact same thing. i tried this at one other light and it did the same thing. when i was at a red light and not the first car in the lane, nothing unusual happened and the engine started back up when i lifted off the brake.

so my question... am i going crazy? i did a quick google search and there were some old articles about audi researching this kind of tech but nothing specific to bmw.

any thoughts?

I’ve noticed the same thing (UK spec car) the car almost seems to predict when the to re-engage the engine.

My two theories have been that the parking sensors are used to detect motion in the cars around you. Definitely would work for when you’re not first car in lane. Maybe could also detect the car behind you creeping closer if you are in front.

Second theory is that it is deliberately very sensitive to any break pedal let off which you will subconsciously do as you anticipate the light yourself.

Either way I find it quite pleasant that it does this predictive behaviour as when I am using ASS it makes for a smoother ride. 90% I switch it off though

[donnyfontaine]

Originally Posted by PNTDG42

I use ASS from time to time. Usually I’m in sport mode though. Don’t be upset it’s there even if you don’t like it… it’s a relatively expensive vehicle and leaving out features that cheaper cars have is not a good look (even if some of you don’t/won’t use it).

it isn't a "feature" for the sake of being appealing to anyone, the EPA either requires it with some type of subsidy, or places get a fine if they don't have it. this isn't something anyone is doing for the customer (outside of hybrids maybe)

[WilcoJunoHotel]

Originally Posted by grooveK

im aware of most on this forum not being a fan of ass,

A.S.S. = bad
ass = good

[Invisiblename]

Originally Posted by Evilmoretea

I’ve noticed the same thing (UK spec car) the car almost seems to predict when the to re-engage the engine.

My two theories have been that the parking sensors are used to detect motion in the cars around you. Definitely would work for when you’re not first car in lane. Maybe could also detect the car behind you creeping closer if you are in front.

Second theory is that it is deliberately very sensitive to any break pedal let off which you will subconsciously do as you anticipate the light yourself.

Your first theory is correct, the car does use the front facing radar to detect the car in front moving off and restart the engine.

[Evilmoretea]

Originally Posted by Invisiblename

Your first theory is correct, the car does use the front facing radar to detect the car in front moving off and restart the engine.

Yeah I was pretty confident on that but can’t explain how OP also experienced this when he was the first car. Other than he let off the brake without realising?

[grooveK]

the odd thing was, when i was third or fourth back, it didnt restart until i definitely started letting off the pedal. ill have to see on monday if the same thing happens lol.

Originally Posted by Invisiblename

Your first theory is correct, the car does use the front facing radar to detect the car in front moving off and restart the engine.