Mercedes-Benz 2011 CL-Class Operator's Manual page 304

Driving systems
302
Vehicles traveling on a different line
DISTRONIC PLUS may not detect vehicles
traveling on a different line. The distance to
the vehicle in front will be too short.
Other vehicles changing lanes
DISTRONIC PLUS has not detected the
vehicle cutting in yet. The distance to this
vehicle will be too short.
Narrow vehicles
DISTRONIC PLUS has not yet detected the
vehicle in front on the edge of the road,
because of its narrow width. The distance to
the vehicle in front will be too short.
Obstructions and stationary vehicles
DISTRONIC PLUS does not brake for
obstacles or stationary vehicles. If, for
example, the detected vehicle turns a corner
and reveals an obstacle or stationary vehicle,
DISTRONIC PLUS will not brake for these.
Crossing vehicles
DISTRONIC PLUS may detect vehicles that
are crossing your lane by mistake. Activating
DISTRONIC PLUS at traffic lights with
crossing traffic, for example, could cause
your vehicle to pull away unintentionally.