I just got C4D R10 and discovered that I can no longer import .C4D files into Unity: It freezes Unity every time. I can import .fbx files, but it keeps discarding all the UV maps except for one if the object is made up of two separate/grouped objects sharing the same texture, and I need the separate/grouped objects as part of a lightmap workaround. Argh! Has anyone else had this problem? A great darkness is settling upon my soul (okay, that was a little bit of an exaggeration).
Yep, C4D files saved with R10 will give Unity an ulcer. It has to be FBX for now, although there shouldn’t be any issue getting your single UV maps into Unity through that. As far as I know, even the “native” C4D importer that worked with R9 went through the FBX interface.
There has been an issue where UV maps aren’t exported if there isn’t a texture associated with them…
Hey it’s been a hard day for me, too. :?
When i do an FBX export with cinema 4D 10. i don’t get my textures in unity,
the unity plugin in not compatible yet.
Norby
But the UVs are intact.
When I import the FBX in Unity, all the materials are created, except they all have the first texture in my set of textures assigned to them. Dragging and dropping the new textures on the material in Unity works fine (UVs and all).
Yes, I just figured that out and feel dumb that I didn’t see it at first. The separate parts of my .fbx model were sharing the same material, therefore the same texture, no matter what I changed it to–easily fixed by creating a new material with a different texture or a different part of the same texture. 
Now I’m back to assigning separate lightmaps to each part, which still works for the time being. I still haven’t found the mesh combiner script that Joachim mentioned in another post. I’m curious to see whether that will work with the C4D multiple UV’s and a single lightmap.