Mercedes-Benz CLK Coupe Operator's Manual page 215

Instruments
Operation
and controls
Driving systems
Notes:
If the engine does not brake the vehicle sufficiently
while driving on a downgrade, the speed you set on the
cruise control may be exceeded. In this case the
automatic transmission shifts down (max. to 3rd gear)
to maintain the set cruise control speed by using the
engine's braking power.
As soon as the grade eases, the automatic transmission
shifts up again dependent on the selector lever position.
Instrument
Driving
cluster display
212
Practical hints Car care
Nevertheless, in some cases you may have to step on the
brake pedal to slow down. In this case the cruise control
is switched off.
Use the lever to resume the previously set speed.
Technical
Index
data