Not sure what Mad Max Mode does, I have the option to turn it on, but haven't. However, I just had a quick blast along the motorway with navigate on Autopilot on, the car waited to it was right on the motorway exit, before suddenly swerving, without slowing down at all. I had thought it was going to take the next exit, so got the fright of my life. Hope Mad Max mode doesn't make it even worse.
Not impressed with nav on ap, however, Auto Lane Change is fantastic. Makes the car so much better on autopilot.