Question: The Audi RS4 quattro is the top tier and highest performing version of some specific generations of the Audi A4 range of automobiles, it slots distinctly above the Audi S4, the original Audi S4, built from 1991 until which year?
Sentence (from "Audi S4"): All subsequent S4s since 1997 have been based on the Audi A4; and as the A4 has evolved from one generation to the next, so has the S4.
Relevant evidence: No