What is the "NTG"?
Mercedes Benz has a Computer system called Cockpit Management and Data system, COMAND for short.
NTG is the code name of Multimedia system and the number defines the generation.
C & E CLASS AUDIO 20
C-Class (W204) with COMAND from 2007 to 2010
C-Class (W204) with Face Lift from 2011 to 2014
E-Class (W212 / C207) from 2010 to 2016