Bizzarrini focused his design effort on the car's aerodynamics in an attempt to improve top speed and stability. The body design was informed by wind tunnel testing at Pisa University as well as road and track testing with several prototypes. The resulting all-aluminium bodywork had a long, low nose, small radiator inlet, and distinctive air intakes on the nose with removable covers. Early testing resulted in the addition of a rear spoiler. The underside of the car was covered by a belly pan and had an additional spoiler underneath formed by the fuel tank cover. The aerodynamic design of the 250 GTO was a major technical innovation compared to previous Ferrari GT cars, and in line with contemporary developments by manufacturers such as Lotus. The bodies were constructed by Scaglietti, with the exception of early prototypes with bodies constructed in-house by Ferrari or by Pininfarina (in the case of s/n 2643 GT). Cars were produced in many colours, with the most famous being the bright red "Rosso Cina".