Never heard of that one...
Thank you for posting!
But I can´t imagine that this was an official prototype.
The well known Janus was a kind of improved version of the Dornier Delta, a very experimantal and progressive design.
This roadster has a pre-war design and looks like a self-built project.
Those late beetle rear lights indicate it has been re-done (or even built?) in the late 1960-1970s.
Would be great to get any more information...