After several years of racing the BMW M1 in Group 5, in 1982 Peter Sauber decided to move up to the top tier Group 3 Prototype class. His first attempt, the Ford- powered C6, didn't fare very well. Sauber returned in 1983 with the C7, this time powered by BMW. While it was an improvement over the C6, engine issues were a challenge. Sauber even took a brief hiatus from sports car racing after the 1983 season.
By 1985, Sauber was ready to give Group C another try, this time determined to partner with Mercedes-Benz. He was very interested in their newly introduced all-alloy 5.0 liter V-8 engine – the Mader M117. Prior to having any relationship, Sauber had asked Mercedes if he could use their new wind tunnel to test his latest chassis, the C8. The folks at Mercedes were impressed enough with what they saw. They were compelled to sign an exclusive arrangement with Sauber for the 1985 season. It would be the first time Mercedes-Benz had returned to sports car racing in 30 years, since the 1955 24 Hours of LeMans tragedy.
In the car's debut at the 1985 24 Hour race it qualified 17th. Even worse, it suffered an accident later in the week that prevented the car from ever seeing the race. The team never entered another race that season.
Sauber committed fully to the C8 for the 1986 season, making every race. They began to show improvements. However, LeMans still evaded them. Neither of the Sauber cars were able to complete the race. They did, however, win the 1000 km of Nürburgring later that season. That victory was incredibly important, as it gave Mercedes-Benz hope, and a reason to continue developing in partnership with Sauber on the new 1987 C9.
The C9 chassis was an evolution of its predecessor, but with completely redesigned rear suspension and bodywork. The engine was an improved version of the Mader M117. The C9 did much better at the 1987 LeMans 24, qualifying seventh and eighth. One of the cars was running in fourth place before gearbox issues forced it to retire very early. The second car dropped out with drivetrain issues in the middle of the night.
Despite the 1987 LeMans outcome, Mercedes saw a glimmer of hope, and doubled down their involvement for 1988 to full factory support. This heavier engagement paid off immediately. They nearly lapped the quick Jaguars at the Jerez 800 km race. The Jerez victory notwithstanding, the high speeds of LeMans proved too challenging for the brutally fast C9. The increased downforce loads on the rear tires caused one of them to burst on one of the C9s on the Mulsanne Straight at very high speeds during qualifying. They did not feel comfortable entering the race after the incident.
For 1989, the Sauber Mercedes team was committed. They came with a newly developed V8, known as the M119. The new engine was equipped with full four valve heads and double overhead cams. Power increased to 720 hp over the previous 650 in race trim.
The German involvement in the 1989 Sauber program was so engaged, they removed all other primary sponsorship and painted the cars to match the scheme of the Silver Arrows of their legendary past. Any issues of the past four years were quickly forgotten. The two Sauber Mercedes C9s qualified first and second on the LeMans grid.
During the 1989 24 Hours of LeMans, the car recorded 247 mph on the Mulsanne Straight. During qualifying with higher boost, the C9 documented speeds of 253 mph. It is believed that the chicanes were introduced to the Mulsanne Straight in 1990 as a result of the frightening consistently high speeds accomplished by the C9 during the 1989 race.
Unlike previous years, the 1989 race was incident-free for Sauber this time. The two cars finished in opposing order but with a very convincing 1-2 victory. Third-place was the Porsche 962C which had won at LeMans six previous times. The C9 had put it two laps down.
It wasn't just LeMans. The car didn't just win races, but dominated. Affirming that dominance, Sauber Mercedes won 7 of the remaining 8 races that season. Not surprisingly, Auto sport magazine declared the sea nine as the racing car of the year for 1989.
Sauber returned to LeMans with Mercedes a few more times, but ultimately transitioned to Formula 1.