The legendary rivalry between Ayrton Senna and Alain Prost was soon to reach its infamous climax. Their deteriorating relationship as McLaren team-mates had prompted defending Formula 1 World Champion Prost to join Ferrari for 1990, and that year’s title battle waged into the final two rounds. To remain as competitive as possible, the Scuderia opted to extend development of its 641 challenger much later into the season. But that came in vain. At the first corner of the Japanese Grand Prix, the pair collided to assure Senna of the crown.

Since Ferrari had come so close to the spoils of glory, combined with a delayed timeline from bringing late updates to the outgoing car, the team top brass felt that an evolutionary—rather than a clean sheet—design was sufficient to remain in contention for both Drivers’ and Constructors’ World Championship trophies in 1991. Disagreeing over this conservative approach prompted Chief Designer Enrique Scalabroni to depart the Scuderia.

That left it to Steve Nichols, who had joined with Prost from McLaren, to steer the creation of the 642. Much of the concept from the rapid 1989 and 1990 cars carried over, but the 642 notably gained revised bodywork and a larger front wing with bigger endplates. It showed promising pace during winter testing—albeit before the new Williams and McLaren had been unveiled. Hopes were high heading into the curtain-raising United States Grand Prix.

The downtown street circuit in Phoenix was dominated by tight 90-degree turns that didn’t suit the Ferrari’s handling balance or performance profile of the Tipo 035 naturally aspirated 3.5-litre V-12 engine. Nevertheless, Prost qualified 2nd behind Senna while new signing Jean Alesi (who’d starred at Tyrrell during the previous two years) lined up 6th. Eventual four-time World Champion Prost converted his grid spot to finish as the runner-up, while an issue with the seven-speed semi-automatic transverse gearbox dropped Alesi to 12th.

In total, five 642s were built. Chassis number 125, offered here, first appeared in the Brazilian Grand Prix in late March. It was taken to Interlagos to be ready on standby as a spare car. In a race famous for Senna scoring his only home triumph after persevering through a failing gearbox and extreme physical pain, Prost banked 4th ahead of Alesi in 6th.

Round three at Imola marked the arrival of a major upgrade for the 642, which gained a tweaked front wing further to more squared off sidepods, a revised airbox and diffuser, plus new front dampers. Chassis 125 was again waiting in the wings as a reserve car. Prost was due to line up 3rd on the grid but on the sodden circuit, spun off during the parade lap. Having stalled the engine on the wet grass, he was unable to take the start. Also set for an early bath, Alesi misjudged a pass on his Tyrrell replacement, Stefano Modena, and was left beached in a gravel trap.

The 642 design would only remain in play for three more rounds, before the Scuderia ushered in the untested 643 for the rest of the year. Internal politics and the new car failing to deliver a sufficient boost ultimately led to Prost exiting the team ahead of the final race in Australia.

Although the 642 did not last the full season, its heart lived on. The atmospheric 3.5-litre V-12 formed the basis of the engine used in the lionised Ferrari F50. Introduced in 1995, the flagship supercar’s F1-derived powerplant was increased to 4.7 litres, generated 520 horsepower, and was a fully stressed member of the chassis.

While in retirement chassis 125 was submitted to Ferrari Classiche for inspection, with certification duly awarded in September 2012. In addition to listing the car’s race history, the accompanying “Red Book” records that the car retained its original chassis and bodywork. It was recognised for being fitted with a correct-specification engine (numbered 91) and seven-speed semi-automatic gearbox (numbered 27).

Chassis 125 now heads to auction notably supplied with a dated Prost race seat insert by Schedoni and spare rear wing (race number “27”), further to front and rear jacks, an engine starter, plus an OMP tyre warming system and blankets. It is also supplied with two full-size sets of tyres (one set of Avons with Speedline wheels, one set of Goodyear Eagles) and a set of narrow-gauge Goodyears, used to make the car easier to manoeuvre and transport. Prior to returning the car to the race track, it is recommended to have the Ferrari fully checked and its safety devices renewed.

Housing one of the most sonorous 12-cylinder powertrains in both F1 and road car history, this pretty 642 offers an incredible route into participation in the renowned Ferrari F1 Clienti programme—where a new owner can best enjoy the naturally aspirated symphony. It would also make for a prized entry into any motorsport collection further to being a star exhibit at any number of concours displays and events.