Sadly, it never went into production.
While Audi Sport has built an RS4, RS5, RS6, RS7, and a TT RS, the automaker has yet to give the flagship A8 the high-performance RS treatment. However, it turns out Audi did technically build an RS8 a few years ago, but it never went into production.
To celebrate 25 years of RS performance models, Audi is hosting a special exhibition at the Audi Forum in Neckarsulm, Germany. Since 1994, the performance division has built 25 RS models starting with the RS2. Six RS wagon models are on display at the exhibition, including a 1994 RS2, 1999 RS4 Avant, 2005 RS4 Avant, 2008 RS6 Avant, 2011 RS3 Sportback, and the new RS4 Avant.
But we're more interested in the 14 rarities on display, including a racing version of the Audi TT RS built in 2011 for the Nurburgring 24 Hours, an RS5 DTM touring car, and the aforementioned Audi RS8 prototype that never made it to production.
According to Audi Forum's Facebook page, the RS8 prototype was based on the fourth-generation Audi S8 and was built in 2013. Being based on the S8 means it packed a twin-turbo 4.0-liter V8 engine producing 520 horsepower, but there's a good chance more power was extracted for the hardcore RS model.
Further details about the RS8 are unknown, but it looks very aggressive in the photos posted by Audi Forum with its massive air intakes, black grille, and bulging wheel arches. The dual-tone wheels are wrapped in performance Pirelli tires, while the ceramic brakes with distinctive orange brake calipers would have provided immense stopping power. Inside, the RS8 prototype features a unique Alcantara steering wheel, while the rest of the cabin is clad in carbon fiber.
It's a shame the RS8 never made it into production, but at least we still have the new S8 to look forward to. Spy shots have shown the new high-performance sedan with barely any camouflage, which is expected to share the Porsche Panamera Turbo's 4.0-liter twin-turbo V8 detuned to around 630 hp. Audi is also planning to launch three new RS models this year, including the new RS7 Sportback, RS Q3, and RS6.