It is reputedly correct and has been stated in several magazine articles over the years. Saying that I have never heard of any comming on the market or even seen one. Am sure if it is right then some one on this site will no doubt confirm it.
I do however believe that it was a model moulded from the final wind tunnel model and as such has no intrernal detail or even windows but was pureley an external moulded shape with wheels. It's primary purpose was I understand to make sure the customer was happy with the colour choice before painting the actual customers car.
Saying that i know some customers had their paint schemes tested full size on the clinic model or a prototype.
Am sure again further information, probably correcting me will be posted.