I am pretty sure if you are in the US your car is a SL550 as a starter. Mine is a 2013 SL550 however I have the same shifter, control, and instrument indicator. The button cycles through E, S, and M as I push it. When the E or S is shown the standard automatic PRND are shown next to it. When it shows M for manual the PRND is replaced with the gear numbers in the display. Depending on how you engage the manual mode, such as using the the steering paddle shifters when in auto mode the displays adds the gears without having to tap the console switch to M. I would refer to the owner's manual for your car (can download from MBUSA or read on board through the display) for the definitive answer,
When I said "When the E or S is shown the standard automatic PRND are shown next to it." I meant shown next to the E or S indicator in the instrument display, not next to the button on the console (where nothing is displayed other than lighting up for R N D or P.
Marie: Thanks for the correction, you are right 550. Also thanks for the answer. Appreciate the time.