Right. In fact it is a Rendez-Vous coachbuilt by Vignale. However, 1956 should be correct: unveiled at November 1956 Turin Motor Show.
That's the car!
But on the Vignale website it's quoted as being introduced in 1955, with small numbers being produced until 1959.
I'll have to dig into it to confirm that it first appeared at Turin in November 56.
You are right that you have published a picture of this car before: it's on p120 of
Fiat 600 fuoriserie.. You describe it there as having been introduced at Turin in 1956 so you've obviously got that from somewhere!
And it has another of those previous-series Italian registration numbers - Brescia this time!
Here are a couple more pictures:
