Mercedes-Benz S-Class 2011 - Manual (Page 306)

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