At the end of the fifties, Fiat needed brilliant mechanics to equip its new convertible and try to compete with the talented and highly regarded Alfa Romeo Giulietta spider. The firm turns to OSCA. Thus was born the 1500 OSCA twin-cam four-cylinder, which would be manufactured by Fiat under license.
This engine was first fitted to a prototype, which took the form of a coupé with an elegant and luminous roof designed by Pinin Farina. This Fiat-OSCA 1500 GT was exhibited in 1958 at the Turin Motor Show. The design of this superb coupe is fully taken from the convertible Fiat 1200 launched at the 1959 Geneva Motor Show and which is one of the many brand new products revealed in Switzerland. Built by Pinin Farina, it will be a great success. It is in line with the 1100 TV cabriolet launched in 1953 at the Paris Motor Show and which will become 1200 TV four years later.

The 1500 version of the cabriolet unveiled in Geneva appeared in the summer of 1959. It was fitted with the OSCA double shaft designed by Ernesto Maserati. A 1491 cm3 mechanics with square dimensions (78 mm x 78 mm). With a Weber carburettor, it offers 90 hp SAE at 6000 rpm and allows the Fiat to reach 170 km/h. The gearbox has four gears, but the first is not synchronized – which is not uncommon at the time. Disc brakes were fitted to the front in 1960. The 1500 OSCA cabriolet differed from the 1200 version by the different mesh of its grille and a wider air intake on the bonnet.