If you pay attention to Le Mans (and you should!) you know about Audi's R8, R10 TDI, R15 TDI and R18 cars. The R8, for example, is one of the most successful racing cars of all time, having won the 24 hour race 5 of the 7 times it competed, in 2000, 2001, 2002, 2004, & 2005. The long chain of wins was broken only by the Bentley Speed 8 in 2003. But that Bentley used a 4.0L version of the Audi V8, there was no works Audi team that year, an R8 still made the podium (3rd place), and Bentley got out of LMPGTP following that victory and has not returned.
All of these Audi cars are mold-breaking, incredible pieces of machinery with impressive race records and fantastic win streaks. But they had to start somewhere, and those beginnings are sometimes very interesting and not always glamorous.
Enter the Audi R8C and R8R Spyder.
In 1997, Audi began researching an entry for the 24 Hours of Le Mans. By 1998, the open-cockpit R8R had been displayed with notable Audi styling cues. It was a show car first and foremost, as evidenced by things like the quad tailpipes and lack of rear diffuser.
But it did look good. Dallara-built, the car had a 32 valve, 3.6L TT V8 good for 610 hp @ 6300 rpm and 516 lb-ft. @ 5750 rpm. Also utilizing a Ricardo 6-speed sequential transmission and a carbon fiber & aluminum monocoque, the car weighed 917.5 kgs (a little over 2,000 lbs). A working version of this performed most of the testing duties to evaluate the platform and components, but was never raced.
The car made its debut at Sebring in 1999, wearing drastically different, less stylized bodywork.
Most of the changes were for purposes of cooling, with a number of NACA ducts being added ahead of the rear wheels to bathe the turbos, while the smaller inboard ducts provided additional cooling for the brakes. It also sported longtail bodywork, a major change from the earlier concept/mule.
The R8R qualified poorly but eventually finished 3rd at Sebring, behind the BMW Motorsport V12 LMR and Dyson Racing's Ford-powered Riley & Scott Mk III.
Another variation of the R8R appeared in the 1999 Le Mans race, sporting further changes to the bodywork. This design would see the return of a number of Audi cues, like the TT-ish headlights and a grille more reminiscent of something you'd see on a production car.
It was also using a shorter nose and tail than the Sebring car, and the NACA ducts were eschewed in favor of turbo intake ducts.
A wild qualifier (this was where Mark Weber's CLR decided to sing some R Kelly karaoke) put the Audis in ho-hum 8th and 11th places. Not horrible, but certainly well below expectations. The race itself was also action-packed, with Peter Dumbreck's CLR also attempting to ascend to heaven just before the Indianapolis corner, leading Mercedes to pull the remaining CLR out of the race and shamefully out of motorsport competition completely the following year. In the end, the R8Rs claimed 3rd and 4th, again bested by the lone BMW (the other car crashed out at 10 AM while in 2nd place) with one of the Toyota GT-Ones securing 2nd.
The R8C also competed in Le Mans that year, its existence as a result of an ACO rule change.
Essentially, over several years of competition, GT1 cars became purpose-built closed cockpit prototypes with very few homologation specials being built. As this was not what the ACO intended this class to be, GT1 became GTS, which had more modification restrictions than GT1 did and required a set number of production cars to be built, not just 2 or 3. At the same time, the ACO created the LMGTP category, a place for the previous GT1 cars, but under more flexible prototype rules.
This prompted Audi to hastily developed a closed-cockpit version of the R8R, which is what the R8C was. It was essentially bet-hedging, as Audi was unsure which class would provide the best opportunity for victory. Slightly more powerful, the TT V8 produced 640 hp @ 6300 rpm; 30 more than the R8R. The R8C cars used the R8R's rear suspension, engine and gearbox, but even with that many starting points was a compromised project from the start, developed in close to 6 months. While Dallara was responsible for the open cockpit car, Audi handed the R8C project to RTN.
Audi Sport UK attempted to iron out some of the R8C's issues a month prior to Le Mans, but the endemic problems with the car, namely airflow and cooling, could not be overcome. The cars could hit 217 MPH on the Mulsanne straight, but were less stable than competitors and had slower overall lap times. Le Mans was the only race the R8Cs saw, with both cars suffering numerous gearbox issues. The first car dropped out after just 55 laps. The R8Cs even qualified much lower than the open cockpit R8Rs; 20th and 23rd versus 9th and 11th, respectively. Ouch.
The poor performance of the R8Cs lead Audi to abandon the program and the LMGTP class, choosing to focus their energies on the R8R, which would become the Le Mans juggernaut R8 in 2000.
And in a mindbending twist, RTN would re-enter this motorsport picture in 2003, as they were responsible for the Bentley Speed 8 - the only car that ever beat the R8 at Le Mans. That's right: an evolution of the failed half of Audi's LM program (but from another VW brand running Audi V8s) stood up and beat one of the most dominant endurance race cars of all time, which descended from the successful half of that same LM program. I'm trying to think of some ridiculous movie plot to compare this to but I can't, because I don't think even Hollywood has tried anything that weird.