You can find information on the assistance graphic menu under "Assistance graphic" More.
If you set the speed, the Assistance graphic briefly appears in the multifunction display.
Vehicles with steering-wheel buttons:
When Active Distance Assist DISTRONIC is activated, one or two indicator segments light up in the stored speed range of the speedometer.
If Active Distance Assist DISTRONIC detects a vehicle in front, the indicator segments, located between the speed of the vehicle in front and the stored speed, light up.