The "RS" initials are taken from the – literally translated as "racing sport", and is Audi's ultimate 'top-tier' high-performance trim level, positioned a noticeable step above the "S" model specification level of Audi's regular model range line-up. Like all Audi "RS" models, the RS 6 pioneers some of Audi's newest and most advanced engineering and technology, and so could be described as a halo vehicle, with the latest RS 6 Performance having the equal most powerful internal combustion engine out of all Audi models, with the same horsepower and torque as the physically larger Audi S8 Plus. Unlike the A6 and S6, however, the RS 6's engines in the C5 and C6 iterations have not been shared with any other vehicle in Audi's lineup. However, for the C7 generation, the Audi RS 6 has the same 4.0L bi-turbo V8 engine as the Audi RS 7, with both being positioned at the top of the Audi S and RS range, and detuned variants of the same engines are found in the Audi S8, Audi A8, and Audi S6.