Linking workflow

Hi guys,

I’ve modeled a car and I’d like to now keep it in its own file, and link to it from other files in which I make different scenes to render it. Mainly I want to go back to the car file to edit its mesh every time I spot something that can be improved, and have that change reflect on the other files, but it is important that I’m able to change the car materials in the other scenes (in one I might be rendering with Lux, in the other with Cycles, for example, plus adjustments).

… but I’m not being able to get that to work nicely! I’ve selected everything and created a Group, then linked to it from the scene files, but to make the car proxy I have to do that for all mesh objects, which are quite a few. Should I be joining everything into one object before? That kind of defeats the purpose of grouping… I tried different things, linking group, linking (all) individual objects, linking the parent of the whole thing, …, and aside from weird stuff like getting duplicates it just seems too complicated for something the user manual describes very simply:

PROXY OBJECTS […] For example, if modeling a car, you may have one person working on the shape of the car (its mesh), but another working on available color schemes (its materials). In this case, you want to grant the painter a Proxy of the object and allow him/her to modify the material settings. […] To make a proxy object for yourself, establish a link to the source object as described above. With that linked copy selected (RMB ) and in view (you can see it in the 3D View), press CtrlAltP and confirm the Make Proxy dialog. The object will be named with the original name plus a “_proxy” suffix. You may now move and modify the proxy.

http://wiki.blender.org/index.php/Doc:2.6/Manual/Data_System/Linked_Libraries

I couldn’t find this answered anywhere, so I guess I’m just doing something stupid… What am I doing wrong?