Recently had a long discussion with ZF transmission specialist. His input was that the 5 speed is the better of the two. Fewer weak points in 5 speed and has less computer controls. Either way I would invest in Dinan transmission software. Shifts are crisper, shift points are improved and you have control of shifts in manual mode.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas