Mercedes-Benz 2011 GL-Class Operator's Manual page 294

Features
292
Do not place several floormats on top of each
other as this may impair pedal movement.
X
Slide seat backwards.
X
To install: place the floormat in position.
X
Press floormat eyelets : onto retainer
pins ;.
X
To remove: pull the floormats off
retainers ;.
X
Remove the floormat.
Infrared-reflecting windshield
The infrared reflecting glass prevents the
vehicle interior from becoming too hot. It also
blocks radio waves up into the gigahertz
range.
In order to operate radio-controlled
equipment, e.g. toll systems, there are
areas : on the windshield that are
permeable to radio waves. In these areas, you
can install radio-controlled systems. These
areas can best be seen from outside the
vehicle by observing the light reflected off the
windshield.