The car in which Ayrton Senna earned a remarkable victory in his home Brazilian Grand Prix in 1991 is set to sell for as much as $15 million in a sealed auction. That day, rain swept across Interlagos, and Nigel Mansell had surged past him at the start before retiring with a gearbox issue. Senna appeared a lock to have his first home victory within reach-a win that had eluded him in seven previous attempts. Yet, with just ten laps remaining, the same mechanical fault that had ended Mansell's race struck the Brazilian. Having lost fourth gear and struggling with fifth and sixth, Senna faced the prospect of heartbreak once again. As the race wore on, the light drizzle turned to steady rain. While others fought to stay on track, Senna's fabled prowess in the wet gave him a lifeline. Wrestling both his car and the treacherous conditions, he fought to preserve his ever-shrinking lead over Riccardo Patrese. By the final lap, what had been a 20-second cushion was down to four, and it looked certain that the Brazilian's luck had run out. Then came disaster: as Senna frantically searched for any usable gear, the stubborn lever finally engaged sixth. Afraid to shift again, he was forced to complete the race in top gear. A win now seemed impossible. But with the quiet ferocity that had become his trademark, Senna refused to give in. For those watching at home, the memory remains vivid almost 35 years on. Families sat on the edge of their sofas, peering at grainy televisions as Senna's red-and-white Marlboro McLaren carved through the rain, rooster tails fanning behind. The car threatened to stall in the slower turns, and without engine braking, it wanted to carry straight on. What followed over the final 2.7 miles of the Brazilian Grand Prix was one of the greatest drives ever. When the chequered flag finally fell, Senna had claimed his first home victory in front of 70,000 ecstatic fans, finishing just 2.991 seconds ahead of Patrese. Overcome by exhaustion and pain, his legs and neck cramping from the effort, Senna had to be lifted from his car by medical staff. Barely able to raise the trophy, he nonetheless experienced what would become one of the defining moments of his career. McLaren would go on to secure both the Drivers' and Constructors' Championships in 1991, with Senna claiming his third and final world title. The historic Interlagos triumph would remain the sole race outing for the car that carried him to victory. At the season's end, its work complete, chassis MP4/6-1 was retired and returned to the McLaren factory, where it would remain for nearly 30 years. Designed by Neil Oatley under the technical direction of Gordon Murray, the MP4/6 was a masterpiece of early-1990s engineering. It was powered by a new 3.5-litre Honda V12 engine producing 720 horsepower at 13,800 rpm, mated to a six-speed manual gearbox and encased in a carbon-fibre monocoque chassis. Nearly 35 years on, it remains an analogue dream-an icon of a golden era in Formula 1. With eight Grand Prix victories and both world titles to its name, the MP4/6 crowned one of McLaren's most successful periods. It was the last car to win a world championship with both a manual gearbox and a V12 engine-a final triumph for a vanishing breed. Chassis MP4/6-1 holds a special place in McLaren's history for its role in one of the sport's most celebrated drives. Remarkably, this near-mythical car left the McLaren collection in 2020, when it was acquired by its current owner. Before being sold, the car was fully recommissioned to race-ready condition by McLaren Heritage and later serviced by marque specialist Paul Lanzante Ltd. It will return to Lanzante (McLaren Petersfield) for further inspection and start-up before being handed over to its new custodian. The car comes with a McLaren Certificate of Authenticity and all original support equipment, including external starter, water tower, remote dash, fuel primer, and engine pre-heater. Ayrton Senna remains Formula 1 royalty-revered for his brilliance on track and admired for his humanity off it. This car stands as a tangible link to his most hard-fought victory, a race that encapsulated everything he was as a driver and as a man. Offered directly by its sole private owner, chassis MP4/6-1 is, without doubt, one of the most significant and evocative Formula 1 cars ever to be offered for sale.