Mercedes-Benz S-Class 2011 Operator's Manual page 306

Driving
304
i
If drive program S or M has been selected,
the ECO start/stop function is always
deactivated.
Activating
X
Activate the ECO start/stop function using
COMAND ( Y
The ECO symbol and the
active
display message is shown in the
multifunction display.
If not all conditions for automatic engine
switch-off ( Y
Stop/Start inactive
i If you activate the ECO Start/Stop
function in the drive programs S or M, drive
program C is selected automatically.
page 257).
Stop/Start
page 303) are fulfilled, the
message appears.