At speed on the highway, there's a hint of wind noise and the steady thrum of pavement from under the tires. While neither is intrusive, the Audi A8 is not as utterly silent as a Mercedes-Benz S-Class. Open the sunroof and interior noise predictably increases, but the A8 arcs through the atmosphere cleanly enough that the opening in the roof creates little turbulence in the cabin. In any case, it's easy to fully immerse oneself in the rich sound emanating from the outstanding Bang & Olufsen audio components.