Fiat and General Motors developed a platform for four distinct-looking vehicles: the Saab 9000, Fiat Croma, Alfa Romeo 164, and Lancia Thema.
While Saab introduced steel beams in the doors for enhanced protection, and Alfa Romeo took only the platform, Fiat and Lancia rushed the project to the production lines. The Thema was more of an upmarket three-box sedan with wedged-styling penned by Giugiaro.

At the front, the carmaker followed the squared-looking overall design and installed rectangular headlights and a Lancia-specific split grille. Its wrapped-around plastic bumper included a set of fog lights, available as an option or standard depending on the version and trim level. The chromed flush door handles and body-colored door mirrors confirmed the car’s premium level from its sides. For the top-of-the-line 8.32 version, Lancia installed a retractable wing-spoiler on top of the trunk.

Inside, Lancia offered the Thema with either a cloth upholstery or a leather-clad interior. Its squared-looking instrument panel sported two large dials and two gauges, complemented on the center stack by three additional gauges depending on the engine version. Since it was a large vehicle, it could accommodate five occupants inside. Unusually for its class on those times was the folding rear bench, which expanded the 440 liters (15.5 cu-ft) trunk to 1,000 liters (35.3 cu-ft).

Under the hood, the carmaker offered a wide engine choice between 101 hp and 215 hp. Ferrari provided the 2.9-liter V-8 unit, and it was carried over from the Dino and enhanced for Thema.