Well, I guess that makes sense - as I said, one of the articles I saw had the year 1966 in it, although the poor on-line translation from Japanese made it hard to determine what that year exactly represented . . . and yet another website said that the car took two years to build, so I suppose a better automotive historical cryptologist than I could have gotten 1964 out of all that.
In any case, it's still ugly.
Great puzzle, as always the research and pursuit of the solution is more than half of the fun.