I believe you need to check the "dynamic routing" as an option in the nav menu. I know that my X5 will change my route if there is traffic issues on my nav. This happens when I have a destination selected. I cannot tell you the steps cause I cannot check the X because it has been at BMW for the last 39 days so I forget how its done. Check the manual for dynamic routing, this may answer your question.

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2012 X5 50i ZAP(2VA, 336, 465), ZTP, ZPP, ZPS(6VC), ZCW, ZRC, 322, 4UB, 4NC, 610
2011 ///M3 Silverstone II
2011 X5 50i(lemon)
-- SOLD --
08 550 Msport
07 X5 4.8I sport
04 545i sport
02 4.4i sport
01 540I M/sport
00 SL500
97 SL500