There's a source mentioning the name Bertone Yo(u)nique! Is this reliable???
I do believe you are correct, this appears to be a better answer than what I had, and having found the document you're referring to I think that's a lot more accurate than mine.
I had this under two names, Unique Ghost was the one I was after. The other was 'Wiesmann Unique Ghost', which was posted on a website that did not allow 'Unique Ghost' as the name because of software, so it was entered as Wiesmann. According to the poster, it had nothing to do with Wiesmann, which is my reason behind denying Wiesmann involvement. I'm guessing that because the name was transferred orally to the photographer, he posted it as 'Unique' rather than 'Younique', which of course would sound the same.
The poster of the images said that no car serves as this base, but evidently a BMW engine does power it. I'm guessing this means that no particular BMW served as this car's donor, just an engine did. Much like Wiesmann really.
I shared all the information I had, I know it was sparse but it was the best I could do, and I have great admiration to Allemano for helping me to solve this too. I think this one's worth 2 points by now, well earned!