Siata was a smaller Italian auto company, some US distribuition in the 50s and 60s, but never much popularity. Now classed as one of the "etceterini" in the Italian car collecting world...
They were kind of like a slightly overgrown Fiat as i recall. Dull powertrains, and such were their downfall.
From a website:
Italian tuning firm, Siata, begun modifying and up-rating Fiat cars in 1926. By 1949 the company had designed its very own car, the Amica. In 1968 it launched a new small sports model based on Fiat 850 components, the Spring. The Siata Spring remained in production until 1975 by which point the company name had changed to ORSA.
http://www.allsportauto.com/english/siata-208-s.php