E-Class (W212) 2010 - 2016: E 350, E 550

How does the whole "Auto Brake Feature" work?

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Old 12-02-2016, 10:27 AM
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Question How does the whole "Auto Brake Feature" work?

I understand there are sensors that detect a pending collision and the car will brake itself, but how does the whole process work? Are the brakes electrically controlled? Does the brake pedal actually move when the car brakes for you? What happens when you realize what is happening and react by putting your foot on the brake pedal, does it feel weird? I assume the rear brake lights come on during this whole process.

Just curious since I never drove a car with this feature.
Old 12-02-2016, 10:35 AM
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The brakes, throttle, and steering are not mechanically connected they are all electronic. When the car auto brakes it will just slow to a stop, now if you put your foot on the pedal it will feel the same as normal, it does not move on its own and only has a short built in range into it to give the appearance of a firm well adjusted brake.

Takes a little getting used to, kind of like the steering, if you notice for example if you it bump on one side the car compensates for it and the steering wheel doesn't jerk around.
Old 12-02-2016, 10:48 AM
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Ah, ok that makes sense. So in the case of using Distronic I can see how the car will "trail" brake to maintain distance, but couldn't grab the concept of emergency braking. All the YouTube videos I watched only shows the car braking, nothing shows what the actual brake pedal does.
Old 12-03-2016, 12:11 AM
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Originally Posted by Rogue Leader
The brakes, throttle, and steering are not mechanically connected they are all electronic. When the car auto brakes it will just slow to a stop, now if you put your foot on the pedal it will feel the same as normal, it does not move on its own and only has a short built in range into it to give the appearance of a firm well adjusted brake.

Takes a little getting used to, kind of like the steering, if you notice for example if you it bump on one side the car compensates for it and the steering wheel doesn't jerk around.
I have to disagree. I have a 2011 E550 with distronic etc.

If I'm using cruise control there is no change in how the brake pedal feels. A couple times I've been driving "manually" and the car in front of me brakes a little so I brake, followed by VERY hard braking by the car in front of me which has kicked in the "auto brake" feature he's asking about.

The pedal DEFINITELY moves differently. It almost feels like it falls to the floor or something. I don't think it's really moving on its own but it's as if suddenly there's no pressure needed to brake 100%. It's hard to explain but the sensation is altogether different than "normal braking".

Man I said brake a lot.
Old 12-03-2016, 05:16 PM
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Originally Posted by cc16177
I have to disagree. I have a 2011 E550 with distronic etc.

If I'm using cruise control there is no change in how the brake pedal feels. A couple times I've been driving "manually" and the car in front of me brakes a little so I brake, followed by VERY hard braking by the car in front of me which has kicked in the "auto brake" feature he's asking about.

The pedal DEFINITELY moves differently. It almost feels like it falls to the floor or something. I don't think it's really moving on its own but it's as if suddenly there's no pressure needed to brake 100%. It's hard to explain but the sensation is altogether different than "normal braking".

Man I said brake a lot.
Right I agree. I probably worded it incorrectly. I meant it like its not motorized, like if you look at the brake pedal while its doing it, it doesn't move, however pressing the pedal while its already braking is of course different because part of that programmed range has already been accounted for.
Old 12-03-2016, 06:52 PM
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Originally Posted by Rogue Leader
Right I agree. I probably worded it incorrectly. I meant it like its not motorized, like if you look at the brake pedal while its doing it, it doesn't move, however pressing the pedal while its already braking is of course different because part of that programmed range has already been accounted for.
Gotcha. In that case we are on the same page!

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