aha, found the answer already on roadfly. "Q" once said:
cars with transmission switch that reads A/M...are put into the S (sport mode) by pulling the gear select lever back to 4 (in the 740i/il) or 3 in the 750/735iLs. The S will illuminate in the instrument cluster display as well.
These cars go into the manual M mode just like yours...except the 740i/iL has an * instead of an M to indicate "winter mode". Winter mode operates basically the same as "manual" mode. To get out of manual mode...the drivers has to move the switch back to A (automatic/economy) mode or move the gear select lever back to D to get out of "sport mode".