AUTOBRAKE !! (yikes!)

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eNate

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I'm trundling along up a modest hill in the neighborhood after dark. The VW in front of me slows and stops for congestion. I'm not creeping but neither am I coming in hot. Just sort of regular, this side of quick.

About simultaneously the "following too close" icon lights up, the car chirps its little warning noise, and the car auto-slams on the brakes. I'd guess I was at least 3 or 4 feet short of the VW.

I was worried the car behind me seemed to have been a little close, and the sudden braking was probably unexpected. They stopped.

I've seen that adaptive / dynamic brake lights can be coded, but the video doesn't make them look too impressive. Anybody know if those trigger automatically if the car auto-brakes?

I'm curious what tripped the auto-brake system in this case. I'm betting it didn't like my approach speed, but I'd think I'd have seen this before now -- it wasn't that out of the ordinary.
 
I noticed this last week that the following car icon was lighting up a bit more than usual and not very close to the car in front of me, maybe it's an algorithm that takes into account weather (but you're in a warm climate, right?), i'm usually riding the gas very lightly so i can modulate any sudden stops.

I'd love to know also what the triggers really are. Perhaps it's just a remnant tolerance of the older camera based system.
 
eNate said:
I'm trundling along up a modest hill in the neighborhood after dark. The VW in front of me slows and stops for congestion. I'm not creeping but neither am I coming in hot. Just sort of regular, this side of quick.

About simultaneously the "following too close" icon lights up, the car chirps its little warning noise, and the car auto-slams on the brakes. I'd guess I was at least 3 or 4 feet short of the VW.
I experienced a similar autobrake event when I had crossed an intersection in heavy traffic such that the rear of our i3 wasn't fully out of the intersection. When the traffic light turned green for cross traffic, I tried to close the gap to the car ahead which triggered the autobrake event. I was stunned by how abrupt the stop was. The "potential collision" icon illuminated followed essentially immediately by the warning chirp and the hard braking. I have seen the "potential collision" icon and heard the warning chirp on several occasions but braked before autobrake occurred. I believe the sensitivity or maybe the warning distance can be set.
 
FWIW, the algorithm should use your speed and closing speed to decide if you're too close and take appropriate action. Safety experts suggest you follow the 2-second rule...stay at least 2-seconds behind any traffic ahead. At 30mph, that's 88', at 60, it's double that. In most places, that will also invite people to cut in front of you, but it is safer. In my nearly 5-years with my i3, it's only done that a couple of times.
 
At those speeds, auto-braking is disabled.

In my case, the car ahead was stopped.
 
If you are referring to the auto-brake function included in the technology package, the first setting that I changed in the iDrive when I got my car was to set that silly feature to warn-only mode and only at the last second. Even then, it still false-triggers at least twice a week for parked cars on two-lane roads, which makes the ACC start braking until I mash the go-pedal to override it.

In terms of the disco-strobing brake light function, there is a setting in Bimmercode for three (IIRC) different thresholds to turn on the extra brake lights. I believe that it was selected by brake force, but don't know if they are determining this by hydraulic pressure or deceleration g forces.....
 
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