I just checked. Using iDrive, I selected, in order, the following:
- Driving Mode
- Configure Sport
Under Configure Sport, I have the option of selecting Chassis, Drivetrain, or Chassis & Drivetrain (default).
Of particular note - I have the combination of Dynamic Damping Control (DDC) and the Active Roll Stabilization (ARS) on my 2013 535xi. On the 2012, you could order the DDC as a $2000 option. If your car does not have DDC, then it is quite possible that you cannot configure Sport Mode as there is nothing to configure with respect to the chassis and therefore only the drivetrain could be changed - no point in turning this on or off via iDrive as this gets done by the act of selecting sport mode with the switch to the left of the gear selector in the first place. The drivetrain does certainly change mode when you switch into the sport mode of the transmission by moving the gear selector to the left, as the shift points allow the motor to rev higher (when still letting the transmission decide to shift) and throttle response also changes. Cars without DDC should still have the switch to the left of the gear selector - but using it will not change the chassis settings - only shift points and throttle response.
2013 535xi, Carbon Black, beige interior, M Sport package, HUD, DDC & ARS
2010 Z4 35i, Crimson Red, beige interior, 6sp manual, Adapative Suspension
2000 528i, Cosmo Black, beige interior, Sport package (retired)