With the dual intent of advertising his newspapers and giving vent to his passion for motor racing, Giusti decided to build a complete car starting from the base of the peaceful Fiat 500 "Topolino". The "Sport" was therefore the first complete car produced under the Testadoro brand, in 1947. It was fitted with the Fiat engine of the "Topolino", of which it retained, in addition to the original crankcase, all the other mechanical components. Obviously the engine was equipped with the cylinder head which was the specialty of the car manufacturer, with radial valves and hemispherical chambers, increased to 660cc. The chassis was also the original one of the "Topolino", although updated and "lowered", according to the advertisements of the time. The “Sport” participated in various races, including the Varese Circuit in 1947.

The "Sport", as often happens with the first works, is stylistically confused and almost "baroque", with a number of openings, air intakes and slits that are almost record-breaking. Very particular is the side view with the four rectangular slits that lighten the lower bar of the side, which is wider than the belt line and flows seamlessly into the wheel arches. The front, also characterized by many openings and voids, has a prominent central part of the "windbreak" type, a typical style of the Fiat of the second half of the 1930s (and which, due to the stoppage in production due to the second World War II, they remained in production until the end of the 1940s), first introduced by the Fiat 1500 6-cylinder and then by the "new 1100". Precisely the volume of the central part of the front appears "disconnected" from the linear volumes, even if a little awkward, of the car. Finally, the "Sport" introduces the style of the two large air intakes that will characterize the first part of the Testadoro production up to the "Drin Drin". Later, also considering the link with Zagato, the testadoro will be characterized by a single central grille.