What a difference 25 years makes juxtaposition of Audi RS4 Avant B5, 1999 & Audi RS4 Avant 25 Years Edition, 2024. Audi Sport GmbH is celebrating 25 years of fast estate cars with a special edition. The original RS4 had a 2.7-litre biturbo V6 modified by Cosworth to produce 380PS. The new special edition has a 470PS 2.9 litre biturbo V6. It will be made in an edition of 250 cars, all finished in Imola Yellow