Stop-and-go adaptive cruise control...

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Moserg

Member
Joined
Sep 25, 2016
Messages
12
Location
Canada, Ottawa
How reliable it is in stop-and-go traffic (say for example in big city during rush hours)? Is it work as BMW explained it or it as usual BS to sell it? (sorry for wording, it is not related to BMW directly, but mostly in general for any sales... )
 
I use it all the time but there are some exceptions:
  • Driving toward low sun and approaching a shadow can give a false positive and kick it out. Just switch to 'dumb' cruise control.
  • At night cresting an overpass the city lights can give a false positive. Just hit resume.
  • Seems to like about 1-2 minutes of 'warm-up' before becoming reliable. Just switch to 'dumb' cruise control for a minute or two.
  • Will bring car to a dead stop so you have to touch the accelerator to resume when the cars move again.

Seriously, I would not have a car without it. Compared to the good it does, these are minor irritations.

Bob Wilson
 
ACC works generally well in stop and go traffic. It has issues keeping the correct distance when another car is moving in your lane. If the car is stopped for more than a couple of seconds it will not move until the "resume" button is pressed or the "electron" pedal is tapped.
 
Compared to most drivers, it is slow to resume on itself from stop, but you can always start things yourself. As said, deep shadows on a sunny day or a low sun angle can give it fits...it is a camera based system, and does not use radar or the US sensors. It will merrily ride right through a red light if there's nobody stopped in front of you, just like any cruise control, and seems to react a bit differently if you were already following someone, or come upon a stopped vehicle (it tends to recognize it a bit later than I'd like, but always seems to be able to stop - maybe a bit stronger than I would if I were doing it myself - I tend to turn it off myself from experience of those situations). Note, a momentary press on the off button will disengage the CC. A second push will turn it off. The car will coast a moment before it starts regen when you disengage the CC by either the off button or using the brake pedal.

I didn't think I'd really like it as much as I have and I'd look for it on my next car. It was in a package on the vehicle I ended up with, otherwise, I might not have tried it.
 
My use of ACC is similar to that described by jadnashuanh. When I see vehicles stopped ahead, I will usually momentarily disengage ACC as jadnashuanh described to control deceleration myself because ACC's deceleration can be stronger than I prefer, even to the point of using friction brakes because regen braking isn't sufficient due to deceleration having been started too late by ACC. I think some of this is due to the limited forward range of ACC's rather low resolution VGA camera which results in ACC not recognizing stopped vehicles ahead as soon as I do.

I have never experienced the warm-up period described by bwilson4web. Our ACC works correctly immediately upon being turned on. As bwilson4web described, our ACC camera can be blinded by direct sunlight entering the camera just like our eyes.

On a couple of occasions, ACC did not recognize slower white box trucks ahead. Had I not intervened, ACC would have happily driven our i3 into the rear of these trucks, so one must stay alert. I now pay attention to the display that shows a red icon of the rear of a car when ACC has detected a vehicle ahead. If this red car icon doesn't appear when I think it should, I prepare to intervene.

Other situations in which ACC isn't perfect is when a vehicle changes out of my lane. ACC will frequently decelerate unnecessarily even though the vehicle has completed the lane change. I usually rest my foot near the accelerator pedal so that I can press the pedal when ACC decelerates unnecessarily, or when ACC is sun-blinded, fooled by a dark underpass surrounded by bright surfaces, or when driving on a windy road with vehicles parked along the side of the road.

ACC should be viewed an a driving aid only. The driver must always be ready to intervene. Even with these imperfections, driving with ACC is much more relaxing, and I would never buy a car without it.
 
It's not perfect, but it's so nice!

I picked up an X1 loaner today that has regular cruise control and in medium traffic I realized how nice the adaptive cruise is.

Someone mentioned changing into "regular cruise control mode" and I have no idea how to do this if it can be done.

Can you?
 
Yes, you can cause the ACC to revert to a 'dumb', normal CC. It's in the manual...I have found that most of the time it says it has stopped ACC, it is the result of a momentary situation, and re-engaging it allows things to continue on. It is described in the user's manual. I seem to remember you press and hold one of the following range buttons for a bit, but I'd have to read the manual to verify. When you restart the car, it reverts back to ACC, assuming you have that option!
 
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