Apart from the use of the 1,475 hp Daimler-Benz DB 605A-1 twelve-cylinder liquid-cooled inverted V-engine, the Centauro differed from the Freccia in having a fuselage of improved fineness ratio and a redesigned wing of exceptional efficiency. This wing was a two-spar structure built in two sections bolted together on the fuselage center line. Metal stressed-skin was employed and the metal-framed statically and aerodynamically-balanced ailerons were fabric covered.
The prototype Centauro was flown for the first time on April 30, 1942, photograph above shows the second prototype pictured at the test center of the Italian AF. Production was initiated early in 1943, the initial production model being the G.55/0 with an armament of a 0.787 in (20 mm) Mauser MG 151 cannon and four 0.50 in (12.7 mm) Breda-SAFAT machine guns. The G.55/0 was succeeded on the production line at an early stage by the G.55/I which differed in having an armament of three MG 151 cannon and two Breda-SAFAT machine guns.
Deliveries of the Centauro to the 53° Stormo and the 353° Squadriglia of the 20° Gruppo had only just commenced when, on September 8, 1943, Italy capitulated, and in consequence this lighter did not see operational service with the Regia Aeronautica. However, production of the Centauro was centered in the area of Italy occupied by German forces, and with the formation of the Repubblica Sociale Italiana (RSI) and the Aviazione della RSI, the lighter was selected as standard equipment for the new air arm, several thousand being ordered.
An autonomous fighter squadron based at Turin was equipped with the Centauro, as were also most of the elements of the 1° and 11° Gruppi Caccia, but production deliveries were limited by shortages of DB 605A-1 engines and the Italian-built version of this power plant, the Fiat R.A.1050 R.C.58 Tifone (Typhoon), and only 105 G 55 fighters had been completed by the time the Allies overran the remainder of Italy.
Among developments of the Centauro undertaken were the G.55/II with five 0.787 in (20 mm) MG 151 cannon, and the G.55S torpedo-fighter, both of which were flown in 1944. The G.55S carried a single 2,176 lb (987 kg) Whitehead Fiume torpedo beneath the fuselage, the ventral radiator bath being replaced by underwing radiators and a two-position tail wheel being provided. Production of the Centauro for export was resumed after the war, a further 85 single-seat G.55As and two-seat G.55Bs being built."