Giugiaro gave up the provocative design of the 1988 trilogy based on the two-seater Aztec spider to develop and reappraise the class of a renowned saloon. Jaguar was chosen for two different considerations: on the one hand, because the legendary V12 Double Six engine used on the Sovereign was excellent and, on the other hand, because the Coventry-based firm had not developed its saloons as much as its competitors. So the aim was to design a car which, observed from any angle and analyzed in every detail, could immediately be seen to be a Jaguar.

For the twentieth anniversary of his company, Giorgetto Giugiaro came up with the perfect way to convey his creativity, both aesthetically and technologically. At the 1988 Turin Motor Show, visitors clamored to admire the results of the "trilogy": the Aztec prototype and the Aspid and Asgard models, provocative creations, the expression of taste and a passion for cars, reflective of classic style features and daringly ahead of their time.

The Aztec, an extreme, radical vehicle, housed a transverse Audi Turbo mid-engine with permanent four wheel drive. The passenger compartment was divided into two symmetrical portions, with two cockpits for the two passengers, who had their own control panel, protected by a fine wraparound screen. The aeronautically inspired side panels were really made the most of, with graphics and level control levers and mechanical apparatus as a "consequence of the need to sculpt the shape instead of drawing it." For this "two-seater space-inspired boat," the designer took inspiration from the concepts expressed in a series of trials in 1959, considered to be highly visionary, both at the time and today.

The Aspid was based on the MPV coupe already explored with the Bizzarrini Manta. Designed on a similar base to the Aztec Spider, the Aspid featured a glass dome that wrapped around the vehicle from the lines of the valance right to the rear mirror. The door was comprised of two elements: the waistline section similar to that of the spider and the upper section, with the same gull wing mechanism as the Aztec, was here hinged on to the line of the valance and opening towards the front of the vehicle.

The trilogy was completed with the Asgard, an MPV space-wagon designed to use the same mechanical parts and engine system as the Aztec and Aspid. The dominating design feature, compared to the NY Taxi and the Mega-gamma, was the disappearance of square shapes, the introduction of soft treatments and flowing connections in line with updated rules of aerodynamics, and a significant development of the glass surfaces. Six fixed seats were provided, as well as two troughs in the floor of the luggage compartment which could accommodate hide-away child seats, set up to face backwards.

The Proto was further embellished in the following version, the "TL" with the passenger compartment finished in every detail. Its looks are those of a 5-door two-window saloon with a markedly sporty character. From the side the harmonious union between the bonnet, windscreen and roof is clearly visible and becomes concrete at the rear thanks to the double curvature of the glass that encroaches on a part of the area traditionally occupied by sheet metal and at the front with the base of the windscreen moved forward. This gives rise to a change in the proportions between the central body and the rest of the car, with a shortened bonnet and tail which makes more room in the passenger compartment. The roof has been designed in glass (to coordinate and visually integrate with the windscreen and rear window): it has varying degrees of transparency that can be automatically adjusted according to the intensity of light on the outside.

The Proto T/TL, designed by Giugiaro and built in cooperation with Seat, was a preview for the medium-sized car, the Toledo, that the Spanish firm put into production in 1991. It was presented for the first time at the Frankfurt Motor Show in 1989 as a "full" epowood model distinguished by the letter “T”. If compared with traditional mass-produced bodies where the divisions of the volumes are always precise, the Proto T/TL is a blend between the classic three-box and the single-box, thanks to the general roundness of the guidelines.