In 1998, Audi announced its intention to enter the 1999 24 Hours of Le Mans with an open-cockpit prototype, the Audi R8R. Following the 1998 race, the Automobile Club de l'Ouest (ACO) modified classification rules due to the performance of GT1-class cars, which had evolved into purpose-built prototypes. The ACO created the LMGTP category for closed-cockpit prototypes, potentially allowing these cars to dominate the 1999 race.
Toyota and Mercedes both committed to the new rules, prompting Audi to invest in the LMGTP class alongside the R8R program, resulting in the R8C project. Unlike the R8R, which was developed with Dallara, Audi turned to Racing Technology Norfolk (RTN) for the R8C’s design, with Peter Elleray leading the project and Tony Southgate consulting.
The R8C shared the 600 hp (450 kW) 3.6-litre twin-turbocharged V8 engine with the R8R, but differed significantly in aerodynamics. The R8C featured numerous intakes and air exits on the sides, thinner wheel arches due to LMGTP tire regulations, and open wheel arches inspired by the Toyota GT-One for improved brake cooling. The cockpit was long and gradually sloping, with raised humps above the driver to maximize aerodynamic efficiency and direct airflow to the rear wing. The rear of the car featured a longer, boxy tail, building upon improvements made to the R8R.
The R8C was completed late and had limited testing time before the 1999 24 Hours of Le Mans test in May. During the test, the R8Cs suffered from aerodynamic instability, causing a build-up of air underneath the engine cover and resulting in lost engine covers at speed. They achieved speeds of 350 km/h (217 mph) on the Mulsanne Straight but lacked overall lap speed, qualifying 22nd and 28th compared to the R8Rs’ 8th and 11th.
Despite efforts to improve the R8Cs in the month leading up to the race, qualifying results were similar, with car no. 10 qualifying 20th and car no. 9 23rd. During the race, both R8Cs and R8Rs experienced gearbox difficulties, but Audi Sport Team Joest managed the issues on the R8Rs more effectively. Car no. 9 retired after 55 laps with gearbox failure, while car no. 10 succumbed to the same issue on lap 198. Both R8Rs finished the race, placing 3rd and 4th, 5 and 19 laps behind the winner, respectively.
Following the disappointing performance of the R8C, Audi decided to focus solely on the R8R program, which led to the development of the successful Audi R8. However, Audi returned to the LMGTP class in 2001 with the Bentley EXP Speed 8, a car visually similar to the R8C but incorporating lessons learned from the earlier project and a shared Audi engine. The Bentley Speed 8 ultimately won Le Mans in 2003, becoming the only car to defeat the Audi R8 at the 24 Hours of Le Mans.
Audi would later return to a closed-cockpit LMP1 car for the 2011 24 Hours of Le Mans, winning the race with the R18.
Only two R8Cs were ever built: chassis No. 101 (car no. 10) and No. 102 (car no. 9), both raced by Richard Lloyd's Audi Sport UK. The 1999 24 Hours of Le Mans was the only competition in which the R8Cs were entered.