Adaptive cruise control (acc) issues scenario 1 first day I was traveling at approximately 70 mph. As I would in any of my other 100 + cars I've owned, I held the cruise control 'set' button expecting the speed to gradually decrease. The Impala much to my surprise, with traffic behind me, went from 70 mph to approximately 20 mph within 7 secs. The traffic behind me was swerving to avoid crashing into me. It clearly states on page 182 of the owner's manual 'reducing speed while acc is at a set speed. 'press and hold setuntil the desired lower speed is reached, then release it. When you hold the set button the speed drops so rapidly there is no possible way you could reduce the speed to only (for example) to 58 mph. Scenario 2 I was following a vehicle with the acc set. Vehicle ahead of me signaled to make a right turn and was merging right to make the turn. As I proceeded to change lanes and go around the vehicle, my Impala slammed on the brakes causing the vehicle behind me to have to swerve to avoid a crash. Scenario 3 referring to the scenerio 2. when the vehicle turning right cleared the camera on my Impala the Impala accelerated aggressively as though I was attempting to pass someone. It was very unexpected and to the point where I felt I could lose control of the vehicle. Scenario 4 when rounding a curve if the acc camera senses a vehicle moving in a parking lot near the road it again brakes harshly for no good reason. Again causing the vehicles behind me to have to react. The Impala will again accelerate aggressively once past the moving car in the parking lot. Scenario 5 in two lane traffic with the acc set, when you're rounding a corner if the camera of the acc gets the car in the other lane in its vision the Impala will again slam on the brakes. When the car in the other lane is out of the camera range the Impala accelerates rapidly.

- Woodruff, WI, USA