I don't agree 100% with the above.
I believe that the ES SE etc editions come with a standard leather steering wheel with Or without the multifunction buttons.
the Sport steering wheel is similar to the M-Sport, so it is thicker than the standard ES-SE steering wheel but it doesn't come:
1) with the perforated leather (M-sport is with perforated leather) and
2) with the M logo on it.
So for me, there are three types of wheels, the standard, the sport and the M-sport.
the sport was as an option in SE editions
E90 Montego Blue 320i N46B20