[Johnny_Cakes]

New purchaser of a 2017 i3. One of my "must have" options was the adaptive cruise control.

Now, let me preface this question with the statement that I know that I am always responsible for the vehicle operation and must remain alert at all times.

That said, assuming normal speeds, good weather, and clear sight lines -- how often does the i3 need intervention to stop? If approaching stopped cars at a traffic light doing 2 MPH, there is obviously not going to be an issue. But what about faster speeds? Is there some point where it just doesn't have time to react (again, assuming normal road speeds)?

Also, are there some situations that it is just bad at? My last adaptive cruise vehicle did not like it when the car ahead exited from the highway.

From doing due diligence and research, I know that the adaptive cruise got better over the model years. I have a 2017.

[vreihen16]

My 2015 needs occasional manual braking when approaching stopped cars at a red light when doing highway speeds. I also enabled TJA, and don't trust it to do the steering for longer than a few seconds while opening a water bottle to take a sip. Definitely not ready for prime time.

Since the ACC is 100% camera-based with no radar, it turns itself off when the sun is low such as around sunrise/sunset and during winter months. It is also sensitive to having the windshield clean in front of the camera, and don't even think about spraying the washer fluid most days.

The best ACC advice that I can give is to learn the steering wheel button that you must hold for ~5 seconds to disable ACC and enable "dumb" cruise control. (On my car with TJA enabled, it is the top right button on the left side of the steering wheel.)

FWIW, the radar-only ACC system being used in some Mercedes vehicles even in 2023 models has a nuisance feature where it disables itself until the next engine start if the radar doesn't detect a vehicle in something like half an hour. People driving out in desolate areas of the western USA curse that feature out, and nobody has found a way to make the system go into "dumb" cruise mode.....

[Johnny_Cakes]

Thanks for the response!!

Originally Posted by vreihen16

My 2015 needs occasional manual braking when approaching stopped cars at a red light when doing highway speeds. .

Can you be a bit more specific? I don't want to learn this the hard way! So assuming stopped traffic, what is the approximate speed where you would be concerned?

Originally Posted by vreihen16

The best ACC advice that I can give is to learn the steering wheel button that you must hold for ~5 seconds to disable ACC and enable "dumb" cruise control.

Great tip. On my previous ACC car, I never did quite learn the correct sequence as it involved a few steps. After a few minutes of trying, I'd hit a combo that worked.

Originally Posted by vreihen16

, and don't even think about spraying the washer fluid most days..

Funny!

[vreihen16]

Originally Posted by Johnny_Cakes

Can you be a bit more specific? I don't want to learn this the hard way! So assuming stopped traffic, what is the approximate speed where you would be concerned?

Long before you feel a pucker mark forming under your butt in the driver seat!

Seriously though, if the car icon isn't lit as you approach stopped traffic at highway speeds, it means that the ACC does not see those cars yet. By the time it sees them, it needs to almost do a panic stop to avoid rear-ending them! You will need to feel it out in your own car, under different driving conditions.

On highways with traffic lights, I manually brake (or tap the brake pedal) to disengage the ACC until the closing speed seems reasonable. Then, I hit resume on the ACC to let it take over and complete the braking. I call it my auto-braking mode.....

[M4_ZMT]

The best way I can describe it, is it's very 2013-developed tech. I also have the feature on my 2022 Honda Accord and it's a night and day difference. The i3 like others have posted, does not look far enough ahead or something (the stopped car thing)- and I don't really trust it except when in stop and go traffic (it does work well in this scenario). I also feel that the distance left for the car ahead even at it's closest following distance, is a bit too far and causes people to cut around you. It's nice to have, but if I could've gotten money off my MSRP by not getting it (mine is '21 so I had to get the tech package to get the adaptive lamps etc), I probably would've forgone it knowing how well it truly functions. For the time, it's fine, but newer systems, in newer BMW's as well have trumped it in a big way.