Mine is always off - I have a 2012...
If I had a 2013, I would always keep it off. A cool experiment would be to see what happened to the fuel economy if I drove a 2013 650xi with the system turned on to see what happened to my fuel economy. I currently get about 11 mpg (+/- 1 mpg), but I think the auto start/stop (A.S.S.
) is a BandAid on a bullet hole. I could be wrong, but I wouldn't tolerate the annyance for a few miles per gallon extra...