[ezmaass]

So, I had a 5 hour round-trip for business today, and I finally had a great chance to really put the ACC Stop & Go to the test. Here were my impressions.

Normal Cruising

The system appears to work like any other normal cruise control when active. You press the button to activate it, reach your desired speed, and set it. Once active, the system just keeps the car at the desired speed until an obstacle presents itself.

Upon coming up to slower traffic, the system gently applied the brakes and matched the traffic ahead. While it detected a car ahead, a little picture of a car was displayed in the dash and HUD. When the car cleared, or I switched lanes to an open road ahead, the car accelerated (quite promptly I may add) back to the set speed.

The little "up" and "down" distance control arrows on the steering wheel were simple to use, and they appear to offer 4 settings - indicating how much distance you'd like between yourself and the car you're following. The default is the most conservative (4 bars), and it honestly felt WAY too far behind. I found that 2 bars felt about right for me. I also found that the car will adjust the distance based upon your speed - so, the slower you're going, it'll keep you closer to the car in front (regardless of bar settings), and the faster you go, it'll space you out farther. Seems like sound logic to me!

Scary Moments

There were one or two moments that were admittedly scary. The first was when traffic came to a crawl. The ACC was set to 75mph, and traffic was moving now at about 20mph. All of a sudden the traffic in my lane cleared (while still being congested up ahead and to the lane on my right). The car accelerated quite quickly towards the slow traffic ahead. While it wouldn't (and didn't) hit the traffic ahead (slowed back down), it would otherwise be considered a poor driving habit (at least to me). The car accelerated far greater than the traffic in the right hand lane, which would have been dangerous if a car pulled out in-front of me in the left lane. I think this is an area BMW needs to improve.

The second semi-scary moment was when a car DID dart out in front of me on the highway. I was keeping my foot near the brake but DID want to see how the car would react, as I anticipated the other car was going to cut me off. I'm happy to save the 5 did just fine. It applied the brakes (pretty hard) to slow the car down. The collision warning icon flashed as well as made an audible alert, but I never had to intervene. The car initially applied the brakes hard and then more gently to allow distance to grow between us. It was a success, and I'm glad to know BMW took into account the likelihood of drivers cutting you off while ACC is active.

Stop & Go

When I reached some heavily congested stretches of highway, I had the chance to see the Stop & Go feature in action, too. The car came to a complete stop when traffic ahead stopped, and it began moving again when traffic moved. I did note that if traffic was stopped for more than a few seconds, the car wouldn't automatically go again - you could get it to go by tapping the gas quickly or pressed "up" on the left steering wheel rocker switch.

Overall Impressions

This system seems to work surprisingly well. I don't usually use cruise control, primarily since I hated always having to readjust it when traffic became an issue. More over, stop and go traffic during rush hour on the highway is terrible, and this system really seems to make it much simpler.

That said, while it appears to work really well, I found that I wasn't more "relaxed." I felt more like a guy beta testing a piece of software - that could potentially cause a life or death situation, no less! It feels VERY unnatural to allow the car to control the throttle and brake with traffic... especially as you're anticipating traffic coming to a complete stop. I found my foot naturally moving into position to stomp the brake... just in case.

A big piece of my comfort level (or lack thereof) is probably due to lack of experience with the system. This was my first extended real-world test. So, perhaps my comfort will grow with time, and I'll relax a bit more when using the ACC Stop & Go. But considering that this is just a system of sensors, software, and actuators, and BMW advises that you really can't ever fully rely upon it, it raises a lot of questions for me regarding both the usefulness and safety.

If one takes the safety concerns to heart, you must always be ready at a moment's notice to intervene. In which case, the convenience factor seems to drop considerably. After all automation is about convenience, and if I need to monitor a computer driving the car, I might as well drive the car on my own?

For those that may get TOO comfortable with this system, taking full use of its convenience, I can see it becoming dangerous pretty quickly. I found myself getting more and more comfortable with the fact that the car would intervene and brake as traffic ahead did. Would I get to the point where I felt TOO comfortable and let my guard down, resulting in a lack of response or slow response if and when the time came where the system didn't respond appropriately?

Anyway, I find the whole thing curious and philosophically interesting. Clearly we're on a path to self driving cars. Google has done it to some degree already, and these technologies are slowly finding their way into mainstream cars while becoming more and more sophisticated. The "traffic jam assist" in Europe is essentially Stop & Go plus the ability to steer. If delegating full throttle and brake control to the car already feels so odd, I can't imagine how much stranger it might feel to give up control of steering (at least at low speed) as well.

A colleague who was riding with me for the trip commented that he felt it could make poor drivers safer, since the distance control aspect ensured you weren't tailgating and there was sufficient time for the system to stop the car. I agree, and I think there are aspects here that actually may make certain drivers BETTER drivers as a result. But I can't help but wonder what will happen as we become more reliant upon this kind of automation.

Anyway, I'm glad I got the feature. I do think I'll use it in limited scenarios - much more than I ever used regular cruise control. Hopefully those considering this feature for their 5 have found this useful. And I'd be curious for others to weigh-in on their experiences with ACC, Stop & Go, etc.

[Tuesday]

I just got rid of an Audi with ACC stop & Go - and I agree with your ultimate opinions.

I really, really wanted this feature and I was so excited to try it out, but I found it to be impractical for the unpredictable nature of LA traffic. I didn't like that in traffic it would accelerate full throttle if enough space opened up and more so I didn't like how sensitive the front impact sensors were. In LA we drive very close to one another, and when you grow up around here like I did you just get used to it. When the car is letting everyone in front of you (even on the closest follow settings) and constantly slamming on the brakes when that occurs, you realize this is a more autobahn-esque feature that can easily be lived without.

[ezmaass]

Tuesday - yes, the scenario you described of accelerating quite quickly when space opened up is true of the BMW, as well.

I found it quite effective on moderately congested highways where traffic was still moving. I also found it more predictable and useful in VERY heavy congestion where traffic is literally at a crawl and it's nice to keep your foot off the pedals. But it's that odd spot in between where traffic may be going 10mph and then 50mph and then back to 10mph in the span of 10 seconds that seems to be scary because the car will fully use that open road to accelerate to its maximum speed and then decelerate with no regard to the context (e.g. still in congested traffic with a lane next to you that's crawling).

As for the traveling distance, I found the 2nd to closest setting to be about what I'd personally do. The closest setting on the BMW was probably a bit too close for my driving style.

[silvercreek]

Great summaries. This is one of the features I'm looking forward to most. I test drove an Audi with it and it blew me away. I did however notice the full throttle acceleration at inappropriate times. I wonder if max throttle is a setting that can be coded?

[Tuesday]

My Audi had 'individual' settings in the MMI for dynamic cruise control. It could either be dynamic, comfort or auto. Even in comfort unless I adjusted the ACC set speed to something much lower when traffic kicked in - it would take every opportunity to shoot back up to freeway speeds. Just the nature of the feature I suppose. I found myself needing to adjust it more than normal cruise. I will admit it's cool as heck the first time the car slows down for you though. But like OP, I never fully trusted it and kept my foot right over the brake pedal.

[AP]

it is good and you get to know how it will react and there will be some occasions when you do need to take over.(at the end of the day YOU are in control not the car!)
Once scenario I'd like to retest (if I have the nerve) is :-
Cruising at say 70mph, you have nothing in front at that time (so no car symbol) but ahead out of range is traffic that is completely stopped.
Will the car brake?
I could be wrong but thought it would stop if there was a car actually in range but if you suddenly come across a stationary object.....
I guess the collision warning system will intervene at that point, its just a scenario that when it confronts me I brake before the cars ACC intervenes (or not!)

but agree its a very good system. By the way you can also press RES to get it going again if the traffic in front has moved off and you've been stationary for more than 3 seconds.
I tend to also use it heavy traffic jams as it saves some effort and you can just steer.

Having the HUD also makes it better as well as you can what its up to without having to look down at the instrument cluster.

[raleedy]

Because whiplash is sooooo relaxing!

[ezmaass]

I agree that one of the things you can do is set the speed lower if you get into heavy traffic. This should prevent acceleration up to high speed if there's a temporary opening.

As for the stopped traffic scenario, I would expect it to work, but you may have some hard braking.

[ErnestHouse]

I love the feature and use on the highway all the time. So glad BMW offers it in spite of LA traffic not being suitable.

Each bar in the 4-bar following distance control is supposed to be a second of following distance. That's why the distance is shorter at slower speeds.

[Chuck W.]

Originally Posted by ErnestHouse

I love the feature and use on the highway all the time. So glad BMW offers it in spite of LA traffic not being suitable.

I agree. I have given up trying to use it in heavy traffic. In the coming years I am betting they will refine it. But until then, it will only be used on the highway with light to moderate traffic.

One thing that I had Chase (Tuesday) code for me was to have one bar as the default when turning it on over the four bar from the factory. Very nice.

[ezmaass]

Originally Posted by Chuck W.

I agree. I have given up trying to use it in heavy traffic. In the coming years I am betting they will refine it. But until then, it will only be used on the highway with light to moderate traffic.

One thing that I had Chase (Tuesday) code for me was to have one bar as the default when turning it on over the four bar from the factory. Very nice.

I agree some refinement is definitely in order for heavy congestion. If they could use those side view cameras to monitor traffic in the surrounding lanes, they could have the system take into account the surrounding traffic speeds. Logic should tell the car not to speed up to x% faster than the surrounding lanes, perhaps, where it may be likely to get into an accident if a car darted out in front of you. I'm sure it's more complex than that... but something to that effect may be a good start.

The nice thing is these cars have so many cameras and sensors now that SO much is likely possible just through developing new code. The question is would BMW retrofit these enhancement via software updates or make you shell out the $$$ by forcing you to buy a new car with features that really just amount to new software.

[BMWrules7]

Originally Posted by ezmaass

So, I had a 5 hour round-trip for business today, and I finally had a great chance to really put the ACC Stop & Go to the test. Here were my impressions.

Normal Cruising

The system appears to work like any other normal cruise control when active. You press the button to activate it, reach your desired speed, and set it. Once active, the system just keeps the car at the desired speed until an obstacle presents itself.

Upon coming up to slower traffic, the system gently applied the brakes and matched the traffic ahead. While it detected a car ahead, a little picture of a car was displayed in the dash and HUD. When the car cleared, or I switched lanes to an open road ahead, the car accelerated (quite promptly I may add) back to the set speed.

The little "up" and "down" distance control arrows on the steering wheel were simple to use, and they appear to offer 4 settings - indicating how much distance you'd like between yourself and the car you're following. The default is the most conservative (4 bars), and it honestly felt WAY too far behind. I found that 2 bars felt about right for me. I also found that the car will adjust the distance based upon your speed - so, the slower you're going, it'll keep you closer to the car in front (regardless of bar settings), and the faster you go, it'll space you out farther. Seems like sound logic to me!

Scary Moments

There were one or two moments that were admittedly scary. The first was when traffic came to a crawl. The ACC was set to 75mph, and traffic was moving now at about 20mph. All of a sudden the traffic in my lane cleared (while still being congested up ahead and to the lane on my right). The car accelerated quite quickly towards the slow traffic ahead. While it wouldn't (and didn't) hit the traffic ahead (slowed back down), it would otherwise be considered a poor driving habit (at least to me). The car accelerated far greater than the traffic in the right hand lane, which would have been dangerous if a car pulled out in-front of me in the left lane. I think this is an area BMW needs to improve.

The second semi-scary moment was when a car DID dart out in front of me on the highway. I was keeping my foot near the brake but DID want to see how the car would react, as I anticipated the other car was going to cut me off. I'm happy to save the 5 did just fine. It applied the brakes (pretty hard) to slow the car down. The collision warning icon flashed as well as made an audible alert, but I never had to intervene. The car initially applied the brakes hard and then more gently to allow distance to grow between us. It was a success, and I'm glad to know BMW took into account the likelihood of drivers cutting you off while ACC is active.

Stop & Go

When I reached some heavily congested stretches of highway, I had the chance to see the Stop & Go feature in action, too. The car came to a complete stop when traffic ahead stopped, and it began moving again when traffic moved. I did note that if traffic was stopped for more than a few seconds, the car wouldn't automatically go again - you could get it to go by tapping the gas quickly or pressed "up" on the left steering wheel rocker switch.

Overall Impressions

This system seems to work surprisingly well. I don't usually use cruise control, primarily since I hated always having to readjust it when traffic became an issue. More over, stop and go traffic during rush hour on the highway is terrible, and this system really seems to make it much simpler.

That said, while it appears to work really well, I found that I wasn't more "relaxed." I felt more like a guy beta testing a piece of software - that could potentially cause a life or death situation, no less! It feels VERY unnatural to allow the car to control the throttle and brake with traffic... especially as you're anticipating traffic coming to a complete stop. I found my foot naturally moving into position to stomp the brake... just in case.

A big piece of my comfort level (or lack thereof) is probably due to lack of experience with the system. This was my first extended real-world test. So, perhaps my comfort will grow with time, and I'll relax a bit more when using the ACC Stop & Go. But considering that this is just a system of sensors, software, and actuators, and BMW advises that you really can't ever fully rely upon it, it raises a lot of questions for me regarding both the usefulness and safety.

If one takes the safety concerns to heart, you must always be ready at a moment's notice to intervene. In which case, the convenience factor seems to drop considerably. After all automation is about convenience, and if I need to monitor a computer driving the car, I might as well drive the car on my own?

For those that may get TOO comfortable with this system, taking full use of its convenience, I can see it becoming dangerous pretty quickly. I found myself getting more and more comfortable with the fact that the car would intervene and brake as traffic ahead did. Would I get to the point where I felt TOO comfortable and let my guard down, resulting in a lack of response or slow response if and when the time came where the system didn't respond appropriately?

Anyway, I find the whole thing curious and philosophically interesting. Clearly we're on a path to self driving cars. Google has done it to some degree already, and these technologies are slowly finding their way into mainstream cars while becoming more and more sophisticated. The "traffic jam assist" in Europe is essentially Stop & Go plus the ability to steer. If delegating full throttle and brake control to the car already feels so odd, I can't imagine how much stranger it might feel to give up control of steering (at least at low speed) as well.

A colleague who was riding with me for the trip commented that he felt it could make poor drivers safer, since the distance control aspect ensured you weren't tailgating and there was sufficient time for the system to stop the car. I agree, and I think there are aspects here that actually may make certain drivers BETTER drivers as a result. But I can't help but wonder what will happen as we become more reliant upon this kind of automation.

Anyway, I'm glad I got the feature. I do think I'll use it in limited scenarios - much more than I ever used regular cruise control. Hopefully those considering this feature for their 5 have found this useful. And I'd be curious for others to weigh-in on their experiences with ACC, Stop & Go, etc.

Good stuff. I have logged hundreds of hours over 4 years of ACC. The new system used the camera.

If you keep 4 bars distance then the system won't scare you.

I find it takes off a lot of stress.

[ezmaass]

I'd be curious to hear from anyone outside the US with a '14 and the new "traffic assist" feature. It sounds like "Stop & Go" here in the US but with the added ability to steer under a certain threshold. I'm really disappointed we didn't get that here in the US.

Can anyone with it provide some feedback on how it works?

I'm also curious if you guys think we'll get it here in the US - either on new models or as even a potential software upgrade?

[ErnestHouse]

Originally Posted by ezmaass

... The question is would BMW retrofit these enhancement via software updates or make you shell out the $$$ by forcing you to buy a new car with features that really just amount to new software.

That software has to run with all the other software and not interfere or slow down the realtime processing already implemented and heavily tested. Getting these scenarios "right" may also require more cameras for stereoscopic "sight". That's a tome more image data and processing. It's complicated and frankly I'd be stunned if it were "only software" and not a whole new processing and vision system.

[ezmaass]

Originally Posted by ErnestHouse

That software has to run with all the other software and not interfere or slow down the realtime processing already implemented and heavily tested. Getting these scenarios "right" may also require more cameras for stereoscopic "sight". That's a tome more image data and processing. It's complicated and frankly I'd be stunned if it were "only software" and not a whole new processing and vision system.

I actually do believe it's just software. I'd be surprised if BMW built the HW for the euro cars different from the US, especially since they had originally announced the US cars would also have this feature and then only backed off due to legal issues. Something tells me the system is perfectly capable but just not enabled (via software). In the manual it talks about the system using the lane departure cameras, which is part of the driver assistance package required to have ACC stop & go.

I guess we'll find out if they decide to go ahead with it in the US - or if someone finds a way to turn it on for US cars!

[immx]

I ordered ACC with stop go on my LCI and since getting my car in September, I have found it a fantastic feature! I use it most days on the motorway.

As someone just said, the bars are roughly how many seconds behind the vehicle in front it will keep you. The most useful part is in stop start traffic. Not having to touch the pedals at all during jams makes a journey a lot less stressful.

[ErnestHouse]

Originally Posted by ezmaass

...I'd be surprised if BMW built the HW for the euro cars different from the US, especially since they had originally announced the US cars would also have this feature and then only backed off due to legal issues. ...

Good point. Did BMW actually say it's because of the suit happy legal culture of the US?

[ezmaass]

Originally Posted by ErnestHouse

Good point. Did BMW actually say it's because of the suit happy legal culture of the US?

I believe so, at least based upon numerous 3rd party accounts that I've heard. BMW had put out a press release in the US stating that the feature would be available on the LCI cars produced in the fall or later, and then later they retracted it for what appeared to be legal concerns; however, they went ahead with providing it in other non-US markets. Leads me to believe that the function is there, just dormant, and could be potentially re-enabled with future software revisions.

[BigKutta]

Thanks for the great writeup! While it is amazing to know how much computing power is in our cars these days, yet our mental state is still not conditioned to accept the power available to us. I barely use cruise control, let alone such an advanced system. For all the reasons the OP mentioned, I would be extremely nervous about using this in US freeway traffic. In a country like Germany, where the traffic laws are strictly adhered to, this system can work almost flawlessly, but in the US, any moron can get behind the wheel and drive any which way they want. This is why we will never be fully used to it here. Unless EVERYONE is using these system (and preferably driverless cars), I am always going to feel nervous.

[ezmaass]

Originally Posted by BigKutta

Thanks for the great writeup! While it is amazing to know how much computing power is in our cars these days, yet our mental state is still not conditioned to accept the power available to us. I barely use cruise control, let alone such an advanced system. For all the reasons the OP mentioned, I would be extremely nervous about using this in US freeway traffic. In a country like Germany, where the traffic laws are strictly adhered to, this system can work almost flawlessly, but in the US, any moron can get behind the wheel and drive any which way they want. This is why we will never be fully used to it here. Unless EVERYONE is using these system (and preferably driverless cars), I am always going to feel nervous.

The whole driverless car issue will be interesting as it slowly creeps into the mainstream. I think it'll take an extremely bold legal move for it to become a true reality. As evidence here, BMW won't even allow the self-steering function of Traffic Jam Assist here in the US for fear over the legal ramifications.

While it's never a pleasant situation when there's an accident, especially if someone dies, it's usually not difficult to determine fault and let the legal system do its thing. But what happens in the case of self driving cars? Who's to blame in an accident where a self driving car hits another, or drives off the road and kills its occupants, etc? Does BMW, or any other manufacturer, want to be in a position of liability for accidents like that on any regular basis? Probably not, I'd think.

Then again, that's where this technology is leading us. And you'd expect that at a purely statistical level, even if accidents DO occur (and they would), they'd be less frequent than those with cars operated by people. But I believe that statistics, alone, wouldn't help people accept the technology. One accident caused by a self driving car would probably be one accident too many. Human psychology is funny that way. Flying versus driving is a great example, I believe - where people feel "out of control" they assume flying is worse than driving; whereas, in reality, driving is actually considerably more dangerous than flying, statistically speaking. But that element of being out of control is unacceptable for some.

Aside from the legal issues, I also tend to believe that we're still far away from cars that can successfully drive themselves in a variety of real world circumstances. While Google, BMW, Mercedes, and others have proven some very impressive self-driving technologies, they're still in relatively controlled and known environments. All of us who have driven for many years have come upon a variety of "unusual" circumstances that have tested the limits of our ability behind the wheel.

As a software engineer by background, myself, and having worked in AI, I find the problem interesting. Typical artificial intelligence, based upon discrete business logic/rules, is referred to in AI as an "expert system." Essentially, the developer of the code has taken into account various scenarios and programmed appropriate responses. Expert systems can get quite elaborate with nested levels of conditional logic, which make them appear impressive, but at the end of the day their major limitation is that of what they're programmed to "know." Clearly, no amount of programming will ever account for ALL of the possibilities that may occur on the road.

So, that leaves us with other types of AI systems, like artificial neural networks (ANN). Neural nets are used in a number of applications, such as handwriting recognition. The concept is based upon mimicking the human cerebral cortex where neurons are "tripped" and fire signals to adjacent neurons, causing pathways to form that recognize patterns of input and hence cause patterns of output. These systems are great at dealing with "fuzzy" scenarios (handwriting is often different and never the same), but they require training. The "weights" between the artificial neurons, forming these artificial pathways, don't exist from scratch - so the system needs to learn, much like a person learns - through trial and error. In AI we call it back-propagation. Essentially you feed the ANN pairs of inputs and outputs and tell it to associate the two as part of its training. So, you can feed a neural net thousands of images of letters, each time telling it which output neuron (representing the correct letter) should fire. This helps adjust the weights and "train" the network. But it only works so well, and again you'll never cover all conditions... but it IS better, in many cases, than expert systems.

We have a variety of other AI techniques, such as genetic algorithms, temporal neural nets, and others at our disposal, but they all share one very major issues - none of them are great at dealing with "zero day" events - meaning, stuff they haven't encountered before. So whether you're programming an expert system with discrete logic, training a neural net, or "evolving" genetic algorithms, they all heavily rely upon past performance and experience with the circumstance to understand how to respond.

On the road, this could be really deadly of course. A cat runs in front of the self driving car, and the car slams full on the brakes to avoid the collision, but the car fails to take into account the 18-wheeler riding 4 feet off your back bumper... something that a human, even if they've never been in that circumstance, could rationalize and "imagine" the potential outcomes, considering those environmental variables for the first time. Unless the AI system had encountered such a scenario in its training or programming, that could end badly, as it likely wouldn't have the ability to rationalize "which is worse, hitting a cat or having a semi slam into me?"

Anyway, sorry for the long tangent, but it's an interesting topic. We're living in interesting times here, as well, where we'll definitely see these issues be contemplated and tested legally. Putting lives in the hands of automated technologies is never easy.

[BigKutta]

Originally Posted by ezmaass

On the road, this could be really deadly of course. A cat runs in front of the self driving car, and the car slams full on the brakes to avoid the collision, but the car fails to take into account the 18-wheeler riding 4 feet off your back bumper... something that a human, even if they've never been in that circumstance, could rationalize and "imagine" the potential outcomes, considering those environmental variables for the first time. Unless the AI system had encountered such a scenario in its training or programming, that could end badly, as it likely wouldn't have the ability to rationalize "which is worse, hitting a cat or having a semi slam into me?"

If the 18 wheeler was driverless, wouldn't it maintain safe distance so as to be able to stop in the event the car in front of it stopped?

I think that we will all be safer when we take the human factor out of driving. Humans are way too distracted and impulsive on the road and I think the technology and the results will drive adoption. I was at a party once and we were talking about the driverless car. I asked what people would do in the car if this were to be available and most replied "read, eat, shave, etc." Only one said "drive", and he was a BMW owner . Most people would be happy to remove themselves from the driving process especially if accidents will be reduced

[ezmaass]

Originally Posted by BigKutta

If the 18 wheeler was driverless, wouldn't it maintain safe distance so as to be able to stop in the event the car in front of it stopped?

I think that we will all be safer when we take the human factor out of driving. Humans are way too distracted and impulsive on the road and I think the technology and the results will drive adoption. I was at a party once and we were talking about the driverless car. I asked what people would do in the car if this were to be available and most replied "read, eat, shave, etc." Only one said "drive", and he was a BMW owner . Most people would be happy to remove themselves from the driving process especially if accidents will be reduced

Haha... Yes, drive would be the right answer for a BMW owner! I'll admit, if it were available I'd use it from time to time - specifically when it's late and raining... my least favorite time to drive.