I was driving a highway distance of 374 Miles mostly two lanes hwy. While driving I had my collision warning, distance between car indicator and adaptive cruise control in use. It did not happen all the time however when it did it was a violent stop. While driving 75 mph. The car recognized there was another vehicle in the other lane. It would give the warning sign and even if I tap the break it would slam on brake so hard that my passenger burn herself with coffee and the rest of us went towards the wind shield. Thank goodness for seat belts. There were 3 people in the car including myself.This happen 1 with AdA cruise control. I disengaged that feature but left the other features on. It happen two more times while returning home with just collision warning and . I am driving about 75 mph. Car doesn't recognized all the cars passing, then all of a sudden the collision warning comes is activated with a fast beep. As if it just saw the car and before I am able to tap the break it slams on break. I have taken it to the dealership and they could not duplicate it. Instead they turn off the feature. I told them it was on the highway , over 75mph, with other traffic. They indicated it was me and not the machine. If it was someone following me while this happened. At the rate of speed I was going and abruptly stopping. I would have died. Or been seriously injured. My car is not fixed. I DO NOT feel safe.