In some cases, this "fake" audio technology is actually put to good use. Audi uses it in their V8 4.0 TFSI. Apparently, when cylinders are deactivated (to improve fuel economy), it produces some unpleasing sounds, so audio engineers fixed it:
Quote:
When the 4.0 TFSI is operating in the four-cylinder mode, two high-end technologies counteract unwanted noise and vibration inside the car: Active noise control (ANC) and active engine mounts.
ANC records the overall interior noise pattern in a precisely differentiated manner at four microphones, and analyzes it to identify potentially disturbing constituents. If necessary, the system then emits an opposing sound via its loudspeakers, which cancels out the original noise so effectively that the car’s occupants cannot hear it.
Of course, the S6 with that engine does make fake engine sounds as well, and you can even adjust how much of that fake sound is produced.