Giampaolo Dallara and Nigel Cowperthwaite designed the F191 as a clean-sheet car. The Cosworth DFR was replaced by an exclusive supply of Judd V10 engines from Engine Developments Limited. The unit weighed 137 kilograms, produced approximately 660 bhp at the start of the season, and exceeded 700 bhp by the year's end. The monocoque was of carbon fibre construction, and the car used a six-speed transverse gearbox developed in-house by Dallara. Suspension was by double wishbone pushrod configuration with inboard dampers at both ends, and brakes were Brembo units with Carbone Industrie pads. The wheelbase measured 2,950 mm, with a front track of 1,805 mm and a rear track of 1,675 mm. The fuel tank held 210 litres, and the overall weight of the car was 505 kilograms.
Like the majority of its 1991 contemporaries, the F191 adopted a high-nose configuration. The car was presented in red with a white horizontal band running along the engine cover, carrying sponsorship from Marlboro cigarettes, Fin-Eco, fuel supplier Agip, and team owner Lucchini's steel manufacturing interests. The Pirelli tyres proved variable in performance, with grip degrading inconsistently over a race distance — a recurring challenge for drivers managing tyre conservation.
Scuderia Italia's drivers for 1991 were Emanuele Pirro, who had raced for the team in 1990, and the Finnish driver JJ Lehto. In the season's first half, both drivers were required to pre-qualify for each grand prix, a legacy of the team's points-free 1990 campaign.
The pair performed strongly in pre-qualifying from the very first round in the United States, going first and second fastest, then qualifying 9th and 10th. Race retirements followed for both at Phoenix. In Brazil, Lehto was fastest in pre-qualifying but both drivers retired in the race, Pirro from an 11th-place running position with gearbox problems and Lehto from 13th with an alternator failure.
The season's defining moment came at the San Marino Grand Prix at Imola. Pirro failed to make pre-qualifying, but Lehto progressed and qualified 16th. In damp race conditions Lehto carved through the field, reaching sixth by lap 22 and ultimately crossing the line third — only the second podium finish in the team's history. At Monaco both drivers qualified and Pirro added a 6th-place finish for a further championship point.
From Germany onwards, the points accumulated from San Marino and Monaco earned Scuderia Italia automatic entry to qualifying without the pre-qualifying hurdle, simplifying the team's weekends considerably. Both Pirro and Lehto continued to score occasional points through the second half of the season, with Lehto taking an 8th at Belgium and Pirro a 10th at Monza.
The season ended in Japan and Australia. At Suzuka, both drivers were eliminated in a first-lap collision with Andrea de Cesaris. In the rain-shortened Australian finale, Pirro finished 7th — less than two seconds behind the sixth-placed Ferrari of Gianni Morbidelli.
Lehto's four championship points from his San Marino podium placed him equal 12th in the 1991 Drivers' Championship. Pirro's single point from Monaco gave him equal 18th. The team's combined five points placed Scuderia Italia 8th in the Constructors' Championship — a meaningful improvement on the blank return of 1990 and a vindication of the decision to invest in the Judd V10 package.
The Dallara F191 demonstrated that Giampaolo Dallara's engineering group could produce a genuinely competitive Formula One car given appropriate investment in power. Lehto's podium at Imola remains one of the most celebrated results in Scuderia Italia's history. The F191's design principles — particularly the in-house gearbox and the adoption of the Judd V10 — reflected Dallara's technical ambitions at a time when the firm was beginning to establish itself as one of motorsport's foremost single-seater constructors.