Just explain to your service manager that you aren't expecting more power from the sport button (as per the M model), just that you are personally not able to detect changes in the shock absorber damping with the sport button on or off and you would like them to check for proper operation of the variable damping.

Presumably this has just started, and hasn't been this way for the past four years of your ownership of the vehicle. It is also possible that it is working fine but that you just can't feel the difference.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue