We were driving on the highway from Chicago to Indianapolis this weekend traveling 70 mph on "Navigate on Autopilot" when suddenly the cars slams the brake. It happened multiple times and the worse was when we were at 70 mph, the car slammed the brake to 50 mph, it scared us and the dogs at the back. There were no cars in front and in the back but there were 2 cars in the right side of the car. Prior to that brake slamming, the car has been notifying to move to the other lane because we were at the passing lane. We were not, we were in the middle lane and the other 2 cars were in the slow lane. Has anything like that happened to you? After that we just didn't activate the "Navigate on Autopilot" and the brake slamming stopped.