6NS is a new option that has been introduced along with the new navigation system that wil be on all cars built from April. Not sure what it does, but I'd guess it will be the same as the F30/31 as they will all share the same navigation. There was a thread in the BMW forum on Pistonheads about it if you're interested (the title was something about deleting sport suspension on an F25 X3 Msport).
Hope this helps.
2016 BMW X3 30d M Sport - Space Grey with Oyster Leather and a 2015 BMW M4 Coupe - 6 MT in Yas Marina Blue with Full Silverstone Leather.