last Saturday, I was driving a Model S. I changed lane without checking the right mirror carefully enough, and a car passed by my side fast. No thing happen to the car, but my wife questioned sharply why the car didn't warn me with sound, like when we are doing parking? Can this be called the safest car ? I don't know what to say to her. Was it because the software not installed, or I have to turn any option on? Or it simply doesn't have this? I think some other cars has this lane change warning.