My car is a 2012 300C AWD. My trunk has been opening by itself as well! I had it to the dealer about a month ago and they could not find the issue. It has acted up again this week and it is there again. Only 4K on it. I read somewhere it may be a key fob issue but that is pushing it since it has happened over night and in my office driveway while I am in the office. Very odd.