At that time, Audi Sport boss Wolfgang Ullrich started to evaluate the options of joining.

With the upcoming American Le Mans Series also providing a stage for the US-market, Audi announced plans in 1998 to compete in 1999, with the R8R and powered by a 550 hp (410 kW) V8 turbo. As it was considered the better choice for a whole race due to less weight and wider tires, Audi ordered an open top roadster from Dallara, to be developed and run by Joest Racing.

Yet, during the fall of 1998, after the necessity of GT1 homologation was dropped in favour of LM-GTP prototypes, regarding the speed and success of these closed GT coupés like the Porsche 911 GT1, Mercedes-Benz CLK-GTR, and the Toyota GT-One, Audi also ordered their newly acquired Norfolk based RTN (Racing Technology Norfolk, led by Tony Southgate) to build a closed-cockpit car using the same drivetrain.

Audi R8R (open top LMP) and Audi R8C (closed top LMGTP) used in 1999. It is one of the most successful sports cars ever (alongside such greats as the Porsche 956/962) having won the prestigious 24 Hours of Le Mans in 2000, 2001, 2002, 2004, and 2005 (five of the seven years it competed). A streak of six straight Le Mans victories was broken-up only by the Bentley Speed 8 (powered by the same V8 twin-turbo engine) in 2003, when the R8 finished 3rd.