# BMW Explained: Active Cruise Control with Stop&Go Function



## tim330i (Dec 18, 2001)

https://www.youtube.com/watch?v=rvWCJbYtq7Q

Relaxed driving even in heavy traffic: Active Cruise Control with Stop&Go function keeps you at a constant distance from the vehicle ahead at all times. If the traffic comes to a halt, the system applies the brakes until the vehicle comes to a standstill and then automatically moves on as soon as the road is clear.

Active Cruise Control with Stop&Go function was primarily developed for journeys on motorways and major roads. Three radar sensors with a range of up to 150 metres permanently scan the carriageway in the direction of travel. When you approach a vehicle in front, the engine management and brakes adjust your speed so that the distance is automatically kept constant ***8211; and if necessary, the vehicle comes to a standstill.

When the lane ahead becomes clear or the vehicle in front speeds up, Active Cruise Control accelerates again until you reach your desired speed. To move off again after the vehicle has stopped, the driver has to give the command to accelerate manually, either by briefly pressing the accelerator or pressing a button. If the stop lasts from 1 to 3 seconds, the vehicle moves off automatically. Up to four cruising speeds can be pre-programmed and called up at the push of a button.

Active Cruise Control keeps your preferred speed constant when set between 20 mph and 130 mhp and automatically adapts the following distance to the vehicle in front of you. The Stop&Go function even controls the speed when the car slows down to a standstill and restarts the engine automatically after a short interval, e.g. in a traffic jam.

On multilane carriageways, the system detects whether another vehicle is only driving in the adjacent lane. Furthermore, if you wish to resume full control of the vehicle at any time, all you have to do is briefly press the accelerator or brake in order to deactivate the system.

*BMW Explained: Dynamic Cruise Control - Not to be confused with Active Cruise Control*

Active Cruise Control with Stop&Go function is not an autopilot. Consequently, if the vehicle ahead brakes harder than expected or if the system detects a critical situation, the driver receives acoustic and optical prompts to take action. Driving in heavy traffic thus becomes noticeably easier and tiring situations such as traffic jams become easier to master with greater concentration.


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## Oaker55 (Mar 7, 2014)

All sounds good on paper but in practical use and interject a$$hole drivers who will try to squeeze a 15' car into a 14' opening, not so much. The system allows too much distance between cars. If you are traveling at highway speeds and said a$$hole tries to move over into the gap, the system will try to throw you through the windshield. Also, on a slight left hand curve where there happens to be car on the shoulder or a car waiting to pull out of a drive, etc you will get a like response. Personal opinion, this is a system not ready for prime time. Also, the comment that all you have to do is press the accelerator or brake to deactivate the system isn't true. The accelerator will override the system but not deactivate it. Only the brake will deactivate it. They need incorporate a way to deactivate the active part so you can use it like a normal cruise control system. As is, the system is unusable safely most of the time.


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## Doodah Fester (Sep 18, 2015)

I largely agree with Oaker. The problems I've encountered are:

1. The system always wants to leave too much distance between you and the guy in front. And not by half a car length or something, but more like two or three times the distance that you would keep if left to your own devices. And that is with the distance control set to the minimum. At max, who knows...

In traffic, this leads to people thinking you are leaving a space on porpoise and they squeeze in. The ACC slams the anchors as Oaker noted and opens up a new distance. Another car sees an opening in front of you and wash, rinse, repeat. Traffic is moving at 65, but you are barely doing 50.

2. Not good at all about deciding who's in your lane and who isn't. If a car in front is exiting the highway and has got his signal on, your bimmer will again throw the anchors out even though he's slowly making his way to the off ramp.

3. It would be nice if there were some indication that the system has slowed the car. It can be quite violent at times, which makes it all the more surprising when its so stealthy. You're cruising along up behind a truck, but 75 yards behind. After a while you notice that you're still 75 yards back and a glance at the speedo says you're going 10mph slower than you thought.


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## ksuderman (Mar 15, 2016)

I, on the other hand, think that the ACC is my new "can't live without feature". I agree whole-heartedly with the limitations that have been pointed out (the ACC *really* needs a _tailgate mode_ to close the gap in heavy traffic as having people constantly squeeze in ahead is annoying a f***). However, I have quickly learned when to override the system with gentle pressure on accelerator pedal. I just spent a week in a rental car without ACC and I was back to my old habit of yelling at other drivers to "pick a f***ing speed already".



Doodah Fester said:


> 3. It would be nice if there were some indication that the system has slowed the car. It can be quite violent at times, which makes it all the more surprising when its so stealthy. You're cruising along up behind a truck, but 75 yards behind. After a while you notice that you're still 75 yards back and a glance at the speedo says you're going 10mph slower than you thought.


On the HUD (I take it you don't have one) your set speed will pop up once you are a few mph below it. There might be a similar indication on the dash, but once you have to glance at the dash you may as well just look at the speedo.


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## Oaker55 (Mar 7, 2014)

ksuderman said:


> I, on the other hand, think that the ACC is my new "can't live without feature". I agree whole-heartedly with the limitations that have been pointed out (the ACC *really* needs a _tailgate mode_ to close the gap in heavy traffic as having people constantly squeeze in ahead is annoying a f***). However, I have quickly learned when to override the system with gentle pressure on accelerator pedal. I just spent a week in a rental car without ACC and I was back to my old habit of yelling at other drivers to "pick a f***ing speed already".
> 
> On the HUD (I take it you don't have one) your set speed will pop up once you are a few mph below it. There might be a similar indication on the dash, but once you have to glance at the dash you may as well just look at the speedo.


But if you have to constantly "override" the system, what is the point?


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## ksuderman (Mar 15, 2016)

But I don't have to constantly override the system though, I mostly override the system when cars are in the right-hand lane taking an exit ramp. No idea why that causes the system so much trouble when you can pass cars in the right hand lane no problem... Even then it is less of a pain than constantly adjusting the cruise manually to match the speed of the surrounding traffic or not using a cruise control at all. I just finished a 6K mile road trip and it was heaven to be able to set it and forget it. It was even nicer the time I had to drive to/from Boston/Logan in the stop and go parking lot that other cities call "rush-hour".


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## Oaker55 (Mar 7, 2014)

So what I am taking from the conversation that this is a system that is designed to be used in stop and go traffic. If this is true, this should be clearly indicated in the information on line. This is a fairly expensive system that a good majority of the people who order it have no use for. It should be designed like other manufactures have to turn off the active part of the system and still use it as a normal cruise control. As it is designed, it is useless to a good number of people who have ordered it. I see no use for a system that if used like a normal cruise control, will cause the violent braking that i have experienced simply because they have designed the system to allow too much following distance and then allows the car to brake itself so violently as it does. This violent braking could cause a rear end collision.


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## ksuderman (Mar 15, 2016)

It can be used in stop and go traffic; this is mentioned in the online order form, the user manual, and the video Tim posted above. Granted, none of those sources go into much detail, but they do say the system will bring the car to a stop if necessary and resume if only stopped for a few seconds. If you are stopped for more than a few seconds you have to press the accelerator pedal slightly to re-engage the system.

I've also never experienced the "violent braking" other people mention, maybe we have different definitions of "violent braking"? I'm sure the braking force applied depends on the hazard the car thinks it is avoiding, but I've never had the car brake hard enough that I would worry about being rear-ended, or been "thrown through the windshield" when that a$$hole driver squeezes into the gap in front of me. The hardest I've encountered is what I would call moderate braking when other drivers are taking an off ramp to the right. That is about the only time I will override the system.

Despite all of its faults, and I agree with all you have mentioned, it is still a must-have feature for me, but then again so is Navigation. Whether others think they are worth-while features is a matter of personal opinion.


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## Oaker55 (Mar 7, 2014)

Doesn't sound like you've used it at 70+ mph.


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## ksuderman (Mar 15, 2016)

Nope, I do almost all of my cruising at 75-85 mph. 

I think our differences of opinion are due to differing expectations. I expect computers to be stupid and occasionally stumble spectacularly at what humans think are simple problems. Therefore I tend to cut the system more slack in situations that you might consider unacceptable. The ACC is only an assistant and can only react to what it senses at the moment, it is still up to the driver to anticipate situations that the computer can't; e.g. people exiting to the right, cars cutting in front. I know the limitations of the system and they are 100% predictable, so I drive accordingly. Do the limitations suck? Yes, but given the alternative I'm still opting for the ACC.


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## Oaker55 (Mar 7, 2014)

*BMW Explained: Active Cruise Control with Stop&Go Function*

Cruising at 75-80 is not stop and go traffic. I'm willing to give the system an occasional break but what I have encountered with this system is totally unacceptable and can be down right dangerous. This is not a computer issue, I deal with those every day. Computers are only as good as the input into them and this software is terrible. The last time I used the system there was a car waiting to enter the roadway from the right and the car just slammed on the brakes for no reason. Everyone in the car thought I was nuts. When I explained what happened they couldn't believe it. I promptly turned the system off and it hasn't been on since.


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## ksuderman (Mar 15, 2016)

Oaker55 said:


> Cruising at 75-80 is not stop and go traffic.


Having used the system extensively I have had the opportunity to both cruise at 85 and sit in stop and go traffic. Also, around Boston having the cruise set to 85 while sitting still on the interstate are not mutually exclusive.



Oaker55 said:


> The last time I used the system there was a car waiting to enter the roadway from the right and the car just slammed on the brakes for no reason.


I have never encountered that, although I typically only engage the system on interstates or divided highways. However, I thought I had read the system won't (can't) detect stopped cars on the side of the road so I wonder if there is something wrong with your ACC? Maybe a software update and/or sensor alignment is needed?


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## Oaker55 (Mar 7, 2014)

That's the only time I use it. Cruise control around town is crazy.


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## Doodah Fester (Sep 18, 2015)

ksuderman said:


> On the HUD (I take it you don't have one) your set speed will pop up once you are a few mph below it. There might be a similar indication on the dash, but once you have to glance at the dash you may as well just look at the speedo.


I do eventually notice the speed indicator. But the one that really catches my eye is when the big car icon comes up, but this doesn't mean anything. The only thing I think it indicates is that it sees a car ahead. Kinda useless since I can see the car too.


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## Doodah Fester (Sep 18, 2015)

ksuderman said:


> I've also never experienced the "violent braking" other people mention, maybe we have different definitions of "violent braking"? I'm sure the braking force applied depends on the hazard the car thinks it is avoiding, but I've never had the car brake hard enough that I would worry about being rear-ended, or been "thrown through the windshield" when that a$$hole driver squeezes into the gap in front of me. The hardest I've encountered is what I would call moderate braking when other drivers are taking an off ramp to the right. That is about the only time I will override the system.


I live in Kansas and do almost all of my driving in the midwest. I've done two serious road trips and a couple of day trips.

You can be all by yourself on a highway and come up behind a slower car as they get ready to exit. If they move slowly enough onto the exit ramp, ACC will break you from 80 all the way down to 30 over the distance of the exit ramp. As soon as the car is out of the way, ACC will floor it back up to 80. If there had been a car behind me, he definately would be asking WTF.

First time this happened I thought the transmission had eaten itself or something.



> Despite all of its faults, and I agree with all you have mentioned, it is still a must-have feature for me, but then again so is Navigation. Whether others think they are worth-while features is a matter of personal opinion.


I do like the system, mostly. But as much as I like it, the parts I don't like are so bad they seem to cancel each other out. You live in the Northeast, and I can't imagine using it up there.

The issues with the system make you think it was programmed by somebody who had never driven with cruise control on before. The distance it allows, the overreacting to changes in situations, or false detects. It doesn't have nearly enough smarts.


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## SteveinArizona (Sep 12, 2016)

Oaker55 said:


> That's the only time I use it. Cruise control around town is crazy.


I have it also, recognize the limitations, but would not want to do without it. I used it the other day on city driving and it worked great. Coming up to a car at a stop sign my 330e slowed and then stopped behind it and a gentle touch on the accelerator restarted it. I do have the HUD and I think it would be a lot less useful without it. Is it necessary in city driving...no. But if the traffic is not too bad it is pretty cool. On highway driving, and I do drive fast, it works great and definitely reduces my need to tell the driver ahead of me to pick a $#[email protected] speed!


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