I noticed that when I have a Mirror modifier in the model, parts that are hidden show a greyed wireframe in wireframe display mode.

Then I noticed that if I don't have a Mirror modifier, the hidden parts are completely hidden.

I think it would be useful to have that kind of feature without needing to use a Mirror modifier.

i asked one of the devs and he replied: "that's a bit unclear for me, face could be hidden but edge not"

sounds like it can't be done in wireframe mode in terms of interface design...
_________________
I'm sitting, waiting, wishing, building Blender in superstition...