ACC (Adaptive Cruise Control) questions

[tlongdon]

Sorry if this has been asked before, but if it has, I couldn't find it!

I'm waiting (a few more weeks) for my 4hs, but I'm impatient to find out the limitations of Adaptive Cruise Control. Mostly so I can get even more excited about my christmas present.

So I was wondering:

1. What are the distances (in metres) of the 3 settings of ACC distance. Does the 'shortest' distance work for nose-to-tail town centre traffic, or does it leave a gap large enough that any old TD&H will slot in front of me? What is the slowest speed ACC will work for that motorway crawling when a lorry has shed a load of concrete on the M4 just past Newbury?

2. What happens if you're in a line of traffic on the motorway traveling at (let's just say) 70mph, and some crazy pulls out in front of you. Does the car brake harshly to regain the pre-programmed distance it was keeping from the car in front? I'm wondering what impact this would have on the car behind.

3. Does ACC radar sensing work on a motorbike if it's in front of you?

4. Can you vary the acceleration when a car pulls back in and you're free to speed up to your previously set mph? If not, is it leisurely (thus mimicking a light-footed economy-fiend?)

and one final, unrelated question (which I again haven't been able to find a specific answer to). All those beeps. Can they each be turned off, or is it all or nothing, or just... all? I see a workaround for the electric boot being to unplug the speaker.

and one final final question. will the pre-heating work if there is a little charge left in the battery but it's not plugged in?

Ta.

 

[maby]

since we have the GX4h, I can't answer the ACC questions, but with respect to the last two - most of the beeps cannot be turned off. Someone has worked out which wires to cut in order to disable the tailgate closing beep, but you are stuck with the rest, I'm afraid! (actually, I'm not afraid - they don't bug me at all...)

Pre-heating will work even if the car is not plugged in, but it does take a big chunk out of your battery - don't expect to get much heat out of a nearly flat battery.

 

[jevel]

1. I don't think the settings are measured in distance, as I see the gap increases with vehicle speed. My guess is that they represent a certain time distance.

I find that the shortest gap is just a little too big for slow traffic. Typical BMW and Audi drivers tend to wedge in just as the ACC tries to catch up with the queue.

2. All depends on the distance to the nutcase. Most of the times I've had this happen, the car just eases back to the original distance again.

3. If the bike is in the center part of your lane, then yes. If it lies far to the side, I've seen it not detect it at times.

4. I haven't been able to find any way to adjust this. It is pretty aggressive, up to the point where it manages to make the ice kick in. It also stresses a bit more than it needs.

-KJ

 

[tlongdon]

Many thanks to you both!

 

[Chrisdy]

Sorry if this has been asked before, but if it has, I couldn't find it!

I'm waiting (a few more weeks) for my 4hs, but I'm impatient to find out the limitations of Adaptive Cruise Control. Mostly so I can get even more excited about my christmas present.

So I was wondering:

1. What are the distances (in metres) of the 3 settings of ACC distance. Does the 'shortest' distance work for nose-to-tail town centre traffic, or does it leave a gap large enough that any old TD&H will slot in front of me? What is the slowest speed ACC will work for that motorway crawling when a lorry has shed a load of concrete on the M4 just past Newbury?

2. What happens if you're in a line of traffic on the motorway traveling at (let's just say) 70mph, and some crazy pulls out in front of you. Does the car brake harshly to regain the pre-programmed distance it was keeping from the car in front? I'm wondering what impact this would have on the car behind.

3. Does ACC radar sensing work on a motorbike if it's in front of you?

4. Can you vary the acceleration when a car pulls back in and you're free to speed up to your previously set mph? If not, is it leisurely (thus mimicking a light-footed economy-fiend?)

and one final, unrelated question (which I again haven't been able to find a specific answer to). All those beeps. Can they each be turned off, or is it all or nothing, or just... all? I see a workaround for the electric boot being to unplug the speaker.

and one final final question. will the pre-heating work if there is a little charge left in the battery but it's not plugged in?

Ta.

As an IAM member, I have always judged separation distance by time. The three distances settings are equivalent to 1.5, 2.0 & 2.5 secs. 2 secs is the 'normal' separation distance for the majority of conditions. The reason time is better than distance is that the time remains the same irrespective of speed, whereas the distance varies depending on speed. In slower traffic, one bar is sufficient, and equates to the distance you should leave, although it does allow some idiots to try to squeeze in front. I therefore use two bars in the majority of conditions and one bar at slower speeds or in town.

The ACC will operate right down to almost stationary and then pick up again if any stop is only momentary. If the car does actually come to a halt you need to press the brake to disengage it, and then get the car to about 25mph to re-engage.

 

[gwatpe]

I can add that when testing the ACC function with a test car in front, If the car in front does stop, the PHEV will pull up behind and stop. After about a second or so the BRAKE message will appear and the following PHEV will have to apply the brake, as it will move forward by itself and probably touch the stopped car in front. It is this necessary action of applying the brake that disables the ACC.

 

[Tweeds]

Does anyone know if the eco button has any impact on ACC acceleration?

 

[jaapv]

I never noticed any, but then, the ECO button is so subtle that it is hard to notice anything at all.

 

[robw2014]

My answers:
1- I find the shortest is fine for around town or crawling in motorway queues - it is happy to follow the car in front as long as it is moving. If it stops, then it disengages and you are prompted to hit the brake. If you start up and there is a car in front, it will happily re-engage ACC at a low speed. If there is no car in front, it will not re-engage ACC until the speed hits 25mph+. As noted in an earlier reply it is time based rather than distance. The shortest can result in the BRAKE warning being displayed if the car in front slows quickly, which is avoided by using the other two settings.
2 - If cruising on motorway and someone cuts in, it will flash up Brake and beep, but so far has reacted fairly sensibly. I do find on motorways that it can start reacting to a car a long way off on the longest setting, so plan to pull out before your speed drops too much, or switch to the middle setting
3- It seems to detect motorbikes happily and on occasions bicycles too.
4- There appears to be no control over how quickly it accelerates under ACC. Even using ECO, where I would expect it to avoid using the ICE, it often accelerates fast enough to kick in.
I find ACC very useful as once set, you can just concentrate on what is going on ahead / around you rather than on your speedo...

Beeps: some can be turned off (each time you start the car) e.g. parking sensors, Lane departure, etc although why would you want to? It is a bit annoying that opening the boot triggers a set of beeps, but I have found that if locked and you use the button on the boot to open it that this opens without any beeps. You can then manually close it avoiding the beeps triggered by auto-closing. I often get out, lock the car, then open the boot...

No idea on your last question, although it has been nice to get into a car that is warm first thing in the morning without having to scrape it first.

Enjoy your 4HS when it arrives.

 

[jaapv]

I can add that when testing the ACC function with a test car in front, If the car in front does stop, the PHEV will pull up behind and stop. After about a second or so the BRAKE message will appear and the following PHEV will have to apply the brake, as it will move forward by itself and probably touch the stopped car in front. It is this necessary action of applying the brake that disables the ACC.

Theoretically it should brake again before hitting the car in front; the brake warning is part of the FCM system and will be followed by a brake action if the driver does not react. Anybody courageous (or foolhardy) enough to try this out?

 

[TRT]

Re question 2, if the car cutting in is travelling slower than you the ACC will apply brakes; if car is travelling faster than you the ACC will gradually drop your car back to reestablish normal distance without braking.