Some 400 De Tomaso Mangustas were produced but only one Mangusta Spyder.

The idea of making an open version was due to the carmaker De Tomaso's desire to present itself in style, with something that would make a spectacle, at the 1966 Geneva Motor Show.

The Spyder version is made from one of the earliest chassis of the Mangusta, of which it retains basically the same mechanical and aesthetic characteristics, differing only in the more cut-off and horizontal rear end.

The open version also retains the gull-wing opening of the engine compartment, and comes in a double color scheme of white and red. Particular is the choice, for a spider, to keep the side glazing in its entirety, with the door support intact, connecting the front and rear of the car, as can be seen when observing the Mangusta Spyder with the doors open.

The mongoose is an animal capable of killing cobras. Legend has it that the car was named after a failed deal between entrepreneur and racing driver Alejandro De Tomaso and Carroll Shelby. De Tomaso had volunteered to help U.S. racer Carroll Shelby develop a new racing car called the Cobra, but for various reasons the project failed and De Tomaso was forced to fall back on a different project with a great desire for revenge.

The bodywork was designed by Giorgetto Giugiaro, who by then had taken over as chief designer at the Ghia body shop in Turin, adapting to the Modenese chassis an earlier design of his that had been rejected by Iso Rivolta, but which had delighted the new customer. The result was a very low line (only 1100 mm in height) that detracted from roominess, but was the right compromise between elegance and aggressiveness and was characterized by a huge windshield and a split hood with a gull-wing opening. Giugiaro on the Mangusta realized a composite aesthetic exercise of flat elements and anticipated the protruding frame enclosing the grille and headlights, a solution later taken up by other manufacturers. With this car the designer transforms and surpasses the curved, sinuous lines he was drawing until recently for Bertone. Such exterior refinement was contrasted, however, by a particularly sparse interior, in keeping with the idea of a road-appropriate racing car advocated by the manufacturer.

Production of the Mangusta began in 1967, at the same time that De Tomaso acquired the Ghia body shop.

A two-door sedan with retractable headlights and very special proportions, with a long hood and a reinforced rear based on the Maserati type 116 chassis. Inside there were four seats, for a 2+2 configuration of pure luxury. While strikingly similar to the Oldsmobile Toronado Thor, with an identical belt-line movement and rear side windows, its front end is somewhat different, where the thinner radiator grille has its motif repeated by a real bumper lower down. The design inspiration for the retractable-lid headlights came from the Mustang Automobile Quarterly. The lid concept is expressed in two fins on the engine hood.

Bertone was commissioned to "clothe" these dimensions in a more modern shape that would, however, still show its ties to the Giulia; this is evident especially in the shape of the roof. Giugiaro, who followed the development of the 1750 up to the construction of the styling model, designed a smooth side characterized by a thin ribbing that starts at the rear wheel arch and straightens out above. The front and back views are simple and uncluttered. The grille, with double circular headlights of the same diameter, recalls the design of the Giulia Sport Special. Neither the engine hood nor the trunk has any decorative frills. After his first two Mazda attempts, Giugiaro made a brilliant show of the three-box four-door sedan theme with the 1750. And did so with a very modern and elegant sedan, so devoid of decorative motifs that it foreshadowed the idea of reduced-to-a-minimum shapes that was to culminate in the FIAT Uno.