Williams' FW14B that won Nigel Mansell the 1992 Formula 1 world championship will be on sale at the Goodwood Festival of Speed.
Winning the opening five races in a row, it became the most successful FW14B ever to be built.
Bonhams auctioning company have revealed the car will not be offered for sale until July 5 when Goodwood gets underway.
Mark Osborne, Bonhams' motorsport director told Autosport: "This is really as good as it gets. This car contributed more towards the championship in 1992 over any other car.
"The fact that it was a great Adrian Newey design, and he is still so utterly relevant today as he was then, means I would say it's one of the most important grand prix (cars) ever to come onto the market."
Bonhams have experience at selling old F1 cars, with the company selling the 1993 McLaren MP4/8 that Ayrton Senna drove in. Bernie Ecclestone reportedly bought the classic McLaren.
Asked if the Williams car could sell for more than the McLaren, Osborne replied: "I'd like to say yes. If you're looking at last year's results, it had Senna, McLaren, Monaco which was a magic combination.
"But the MP4/8 wasn't a high point in McLaren design. Whereas the FW14B is without question the high point."