This is the 1969 Siata Spring which we all know so well.

Siata Spring 1

The car was introduced in 1969 as "Beat" but that name did not last.
The images from magazines (Quattroruote):

Siata 850 Beat

Siata 850 Special Spring

I have letter from the importer to the dealers and a "folder" for you too; click on the letter to enlarge

Siata Spring 0

Siata Spring, de folder

Siata built some other Fiat 850 derivatives too:
Siata_850-Coupe-2+2

Siata 850 Coupe achter

The rear end looks a lot like an Opel-rear.