Well,... as many of zeiss lenses nowadays are made by Cosina in Japan, this may not be a major topic of discussion nowadays. But the comparison between German/Japan used to be quite in vogue especially for the lenses of Contax which had exactly same type of lenses made in these two different countries.
Even though Zeiss officially announced that there's no difference in these two, German-made lenses were generally considered to be superior to the other, and this seems to be reflected in the second-hand market price easily seen from Ebay.
As an enthusiast for Carl Zeiss lenses - to be more precise - an enthusiast for Contax and Hasseblad lenses, I had many occasions that these two different types make quite remarkable differences, but I would admit that this can be quite subjective depending on the person.
There are still some recent lenses made in Germany, just as Planar 1,4/85 ZM and Distagon 2,8/15 ZM, and I think the outstanding price of these lenses reflected something that can be only found in German-made lenses, even though they may deny the "something".
I just want to know what you guys think about these German made lenses of recent versions, if you think these will have such difference still today, or if you might have witnessed something from them.