In the absence of any contribution from anyone else so far, I just wanted to share my findings. I have not found any mention in any messaging boards of which Glow Plug should be used with my car. The general theme had been that Beru and Bosch are better then NGK. After search high and low for a Beru or Bosch part that would be compatible with a 2011 W212 E200 CDI, I eventually went to Beru and Bosch catalogue search and was shocked to find that they do not list any glow plugs for my model!
I then proceeded to the NGK catalogue search and found that their recommended glow plug had the following associated part numbers:
Stock Code: 9970
Mercedes Part Number: A0011596601; 0011596601; 0011595801; 0011595701
Other Part Number: 180ME0100; 180ME01000009
Boy, these are not cheap. Not even going to try MB.
ECP: 438220246: £44.49 each
GSF: 180ME0100: £44.80 each
I'm getting my 4 cylinder E200 glow plugs's as well as O2 Sensor replaced this morning. Is there any other work that should be undertaken at the same time? I assume the intake manifold does not need to be removed in order to access the glow plugs?