The optional Harman Kardon Surround Sound System offers perfect three-dimensional sound in your BMW 3 Series Touring and opens up a whole world of listening experiences. A treat for the ears, even at high speed. Up to 16 speakers (600 W output) fill the interior of the BMW 3 Series Touring with brilliant-quality surround sound. Compared with the regular hi-fi system, the Harman Kardon system has been further optimized in terms of sound quality and is visually distinct. It includes two additional mid-range speakers and five extra tweeters, all of which have high-quality aluminum diaphragms and thus develop a significantly more refined sound pattern than the regular hi-fi system. Luxurious panels made of anodized aluminum in the mirror triangles bearing the lettering define the appearance of the Harman Kardon Surround Sound System. The use of metal panels with a hexagonal structure serve to optically upgrade the interior. The Auravox technology enables vehicle-specific and speed-dependent equalizing in the bass register, giving a fine level of compensation for driving noise.