When a car is being designed, there comes a moment when the sketches are turned into a tangible model. Nowadays this is done with clay or a synthetic derivative thereof. In the past, this was done in wood and plaster and that happened, certainly for Italian car manufacturers, often at specialized companies. One such company was "Alfredo Stola Modelli Dimostrativi In Legno Per Fonderia E Carrozzeria". They started around 1920 with wooden models for Lancia and later Fiat and Pininfarina became frequent customers. Find out more about their history HERE.

On their site you'll find these pictures, important moments in the development of the Fiat 850's (unfortunately I haven't found anything of the Berlina yet):

Fiat 850 Coupé studio torino master

Fiat 850 Spider studio torino master

Fiat 850T studio torino master

Fiat 850T studio torino master

Of course they wanted to make sure it was a nice car:

Fiat 850 T Stola wielrenners
Yes, as a support bus for their cycling team.