The 2010 Audi S4 accelerates quickly from any speed, and it is probably the acceleration, the Lexus IS350 and Mercedes-Benz C350. But it is not with the BMW M3, the Lexus IS-F or the Mercedes-Benz C63 AMG. RS4 is the task at hand. The engine is a distant, pleasant sound, complemented with the slightest trace of compressor whine when accelerating. It is discreet enough to distinguish the S4 as a comfortable long distance cruiser. But we would enjoy an additional acoustical feedback from the engine compartment.