Mercedes-Benz S-Class Operator's Manual page 279

PLUG-IN HYBRID operation
277
Vehicles with an electric motor generate
much less driving noise than vehicles with
internal combustion engines. As a result, your
vehicle may not be heard by other road users
in certain situations.
Depending on the vehicle's equipment and
country-specific regulations, the vehicle can
be equipped with Acoustic Vehicle Indication.
Acoustic Vehicle Indication generates a cer-
tain sound at a speed between 0 and 20 mph
(30 km/h). This helps other road users, par-
ticularly pedestrians and cyclists, to hear your
vehicle better. The sound can also be heard
inside the vehicle.
The volume depends on the engine speed.
The faster you accelerate, the louder the
sound is. At a speed of over 20 mph
(30 km/h) the sound is switched off. Above
this speed, the natural sounds from the vehi-
cle are sufficient that it can be heard in good
time by other road users.
Z