In 1955 Bertone turned in the final design for the B.A.T. project, a series of prototypes which represented the peak of styling creativity at the time.The B.A.T. 9 did away with the marked wing lines of the previous models in favour of a cleaner, more sober line. The tail fins, which in the other two models, 5 and 7, had a real wing-like look, were sized down into two small metal plates. Bertone transformed the highly creative styling of the two previous B.A.T. models into design credibility, abandoning the extremes of the other designs. The more rational, less artistic design of this prototype, however, does nothing to diminish Bertone's creative contribution to the Italian school of bodywork design.

source: Bertone