The best way to design an automobile may be with a wheel at each corner, but it’s not the only way. Behold the X-chassis configuration of the 1960 Pininfarina X. 

Batista “Pinin” Farina, who legally changed his last name to Pininfarina in 1961, was among the most popular and productive Italian coachbuilders of the classic postwar era, with clients ranging from Fiat to Ferrari to Cadillac. Streamlining was a frequent area of design exploration at the time, naturally, and in 1958, his company partnered with Professore Alberto Morelli of the Politecnico di Torino to identify the ideal aerodynamic design. The result was the 1960 Pininfarina X, also known as the PFX.

Since a teardrop is said to be the optimum aerodynamic shape, Morelli casually tossed away the conventional automotive chassis layout with a wheel at each corner and adopted a rhomboid or X-chassis configuration, above. (Hence the name Pininfarina X.) There was one steering wheel at the front and a single drive wheel at the rear, with two more wheels toward the center to complete the diamond form and steady the platform. The single prototype was powered by a 1089cc Fiat inline four with 43 hp and a four-speed manual gearbox, installed diagonally in the chassis to maximize cabin and cargo volume. Overall length was not quite 170 inches with ample room for four adults.

The large tail fins at the rear were no styling flourish, Pininfarina reported, but were required for stability, in part due to the extremely slippery shape. The claimed drag coefficient was an impressive .23 (.219 according to one interview with Morelli) but the car’s highway behavior is essentially a question mark.

It’s said that Batista Pininfarina frequently drove the PFX on the road while shopping it around to various carmakers, but there were no hand-raisers for the 1-2-1 rhomboid design. However, the experiment did lead to a second Pininfarina-Morelli collaboration in 1961, the conventionally four-wheeled Pininfarina Y, which was based on a standard Fiat 600 platform (below). Both the X and the Y prototypes are still in existence today.