The Sauber Mercedes C9, a Group C prototype race car, was used for three seasons (1987-1989) in the World Sportscar Championship and the 24 hours of Le Mans. In 1989, the Sauber C9 achieved its greatest success by winning both the drivers' and teams' WSC titles and the Le Mans 24h race. It was the second and last Mercedes car to win at Le Mans after the 300 SL in 1952.
The C9 was an evolution of the C8 design. Featuring changes to both the aerodynamics and the chassis, the engine was also lightened compared to the previous generation as KKK turbochargers became more efficient. It produced approximately 800 hp, an outstanding number for a car weighing only 905 kilos. The team also changed the car's color scheme to the traditional Mercedes "Silver Arrows" design for the 1989 season. Repeating the result of the original Le Mans’ Silver Arrow 300 SL, the C9 managed to win the 1989 24 Hours of Le Mans.
During the 1989 Le Mans race, the Sauber Mercedes finished first, second, and fifth. The #63 car won the race with 389 laps around Circuit de la Sarthe during 24 hours of racing, with Mass, Reuter, and Dickens as the drivers. Mauro Baldi, Kenny Acheson, and Gianfranco Brancatelli finished second in the #61 car, five laps behind the winners. The car reached a top speed of 400 km/h (248 mph) on the Mulsanne Straight, one of the highest top speeds in the competition's history at Le Mans. In 1990, two chicanes were introduced at Mulsanne Straight due to this speed and the WM Peugeot's 1988 record of 405 km/h.
The Le Mans race was not part of the 1989 World Sportscar Championship. In the championship, Sauber Mercedes won seven out of eight races, missing only a victory at Dijon-Prenois. Jean-Louis Schlesser won the driver's championship that season, with three other drivers (Mass, Baldi, and Acheson) occupying positions from P2 to P4. In the teams' standings, Sauber Mercedes dominantly took the title.