Adaptive cruise control?

[D's RS5]

I was just driving in town yesterday. this car crossed the street, entered the middle lane and tried to merge into my lane.
Apparently the car was too close to me, because the brakes locked up by themselves with my foot on the gas pedal. then the brakes released themselves right after...
I did not know what's going on with the car since I was not aware that the car did that...
I tried to look it up about this function. It seems like to be related to ACC or the braking guard, but ACC was not set at that time.
Any ideas? I am very curious to find out exactly what that is.

[JamesRS5]

You can deselect the braking in MMI. It's pretty wild in its decision making.

[D's RS5]

I think I will do that. I can brake for myself LOL
Thanks a lot.

[superswiss]

Yes, that's the braking guard. Even without ACC engaged it continuously monitors the cars ahead of you and if it detects an impending collision it alerts you visually and auditory, but if there is not enough time or it doesn't see you make an evasive maneuver than it automatically performs an emergency braking. The feature can be partially or completely turned off in the MMI under the Driver Assist settings. You can turn off the automatic braking, but leave the warning on or you can turn it off completely. Personally, I like the feature. It has on several occasions cut down my reaction time when somebody performed a stupid maneuver and the whole traffic came to a sudden stop. It's a piece of mind.

EDIT: It also turns off if you put ESP in Sport mode. I do that when I go for a run through the canyons as in those environments it sometimes mistakes moving bushes or fast changes in scenery or even an oncoming car for an impending collision. It's no fun when it slams the brakes going around a fast corner.