2012 X5 Diesel
 

Im sure its been asked quite often but I cant find any posts on the topic, anyone know how much of a redesign or what changes if any the Diesel X5 will have? And will there be Stop/Start function built for city driving ??

Not sure why there would be a start stop function for city? Are you thinking Hybrid?

Go test drive a gasoline Cayenne. It has start/stop for the city. Every time you come to complete stop the engine turns off until you let off the brake. You can of course disable this. I guess Toyota has been using this for a long time.
I found it a bit unnerving, but i suspect you get used to it. I felt like people on the street sensed that I stalled the car.
Anyways back to OP, not sure why that would be introduced specifically to diesel first. Star/stop didn't make it to gasoline MY2012 cars.

Stop/start systems provide significant gains on EU fuel economy tests, so they are rapidly becoming standard equipment across brands and models to boost their government ratings.

Apparently these systems have little or no effect on EPA test results, so the technology is slowly making its way into conventional vehicles here due to concern for public acceptance. Hybrids have obviously had this here for years, as the gas engine shuts off whenever it is not needed, whether in motion or at rest.

Regarding the BMW diesels, there are rumors of a tri-turbo coming, but I would be surprised to see it in the next few months.