I love so many things about my M6, but I hate the collision avoidance (automatic braking) system. It hasn't prevented any accidents and has almost caused several by slamming on the brakes when unnecessary. To be honest, I had a bad habit of passing too closely by cars making a right hand turn. When I first got the car, it slammed on the brakes (like 45 mph to 5 mph) several times in the first 2 weeks of ownership doing this. Every time the car turning had already cleared my forward path when the brake were slammed on. I considered it a good safety retraining for me to break that habit. I still turned it off every time I drove the car for weeks but stopped because it's not a simple procedure to do that, you have to turn several features off and navigate through the menus. I would be happy if there was a single dash button to defeat it like there is for traction control.
The last time it overreacted was just a couple weeks ago in city traffic. I was stopped behind many cars at a red light. The light turned green and everyone started to go. I'm not sure why but someone up ahead suddenly stopped. Well there was the accordian effect with each car having to brake harder and harder the further back you were. I was only going about10-15 mph and there was about a 2 car length gap between me and the car ahead when they braked hard. In a split second I thought "Oh sh*t", then just a fraction of a second later I could tell I was good, that I could stop in time. But Oh No, the car decided I couldn't and locked up the brakes. I almost got rear ended by the car behind me.