I didn't order my vehicle with anything other than the standard 6 speaker system, and I have to admit that I didn't crank the audio system during my test drive. I sort of assumed that whatever basic stereo that came with the 3 series would be at least the equal of the stereo in my current Falcon - maybe this was naive.
For reasons I won't go in to right now, during my time waiting for my vehicle to arrive, I've had occasion to play with both a new X3 and a 116i. Both cars only had the standard stereo system. In the X3 I found that the sound felt like it lacked clarity and was distant. I spend a lot of hours in my car (about 40,000kms per year) and I spend a lot of time listening to audio books or podcasts and I found that the quality of voice was not all that great.
Conversely, the 116i had a great sound even out of the base line speakers. The smaller car had a much nicer base reverberation when I put on music that would use it, though with the base tone turned up too much it would begin to distort - certainly not a douf-douf car by any stretch of the imagination.
320d Luxury, Sapphire Black, Black Dakota, Music I/F, Pro Nav, Ext Connect, Sunroof, HUD, Lane Dep Warning, Rear Cam, Internet.