Solved TGF-486: Fiat 1100 BLR based, Advertising car by Castagna.

[4popoid]

Make that a fleet of at least FIVE different Tre Testa vehicles, assuming this model was of an actual vehicle.

[Bill Murray]

Yes, the mystery deepens and I would say the fleet numbered at least 5.

I also Googled the address found on the latest Fiat and that returned no result either.

I did find the hood ornament below, Buick, 1946, which is the closest I have come across so far.
Definitely not an exact match but close.

Bill

[Iluvatar]

In my opinion there were at least THREE Tre Teste cars joining this 1950 Giro di italia tour.

I am quite sure that at the very left of this photo there is even a second smaller car...

I think you are correct grob.  The car on the extreme left does look yet another Tre Teste vehcle, and, judging from what can be seen of the left front quarter, different from any previously posted.  So adding the vehicle with the elevating roof, which is different from any of these three, we now have a fleet of at least FOUR different Tre Testa vehicles.

IMO there is no vehicle with elevating roof. If you look at the pictures, the "grille" on the roof ends on the rear: it's only a decoration. So the "high roof" car is always the same!

[Iluvatar]

I did find the hood ornament below, Buick, 1946, which is the closest I have come across so far.
Definitely not an exact match but close.

That hood ornament was common on post-war "fuoriserie". I remember some Bertone cars with it around 1947.