Its part of the Sports Package, and the only way to buy it in the US.

From the US website:
Sport Package:
19 x 9.0 Star Spoke (Style 212) light-alloy wheels, and 255/50R-19 run-flat all-season tires
10-way power-adjustable front sport seats with 2-way manual thigh support adjustment, and memory system for driver’s seat, steering wheel and outside mirrors
Power tilt/telescopic leather-wrapped multi-function sport steering wheel
Adaptive Drive: includes Active Roll Stabilization and Electronic Dampening Control
Anthracite headliner
Shadowline trim

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2013 X5 35i M Sport