Why does the Mercedes-Benz S400 make a hissing sound?

[LeBrantley]

Mercedes-Benz S400 may produce a hissing sound for the following reasons: Tire noise: If it's a dull thumping sound, it is mostly due to tire tread deformation, bulging, severe wear, or insufficient air pressure; if it's a tapping sound, it may be caused by small stones stuck in the tread; if there's a metallic clashing sound inside the tire during driving, it might be due to damaged shock absorbers or bearings, and it should be inspected and repaired at a 4S shop promptly. Engine noise: In this case, either the engine components or the moving mechanism has an issue. Not only is the repair complicated, but it also requires a professional technician to diagnose.