Question: what is the difference between audi rs4 and s4?
Answer: Engine & trans This all-new model has a 2.9-litre twin-turbo unit, which shares much with the Audi S4 and S5 models (they run a 3.0-litre turbo - the engine in the RS 4 is a smaller capacity and has a shorter stroke, but adds a turbo over the lesser S models). It's no V8, however.