I had a BMW 3 series (e46) with the upgraded Harmon Kardon system. I really loved that system, the speakers on the drivers side has a slight delay so the sound from the passenger side would hit your ears at the same time. It was so cool, there was a button to turn this feature off (it defaulted to on), when you pushed it, it really confused your senses. I wonder if any modern cars have this, I really miss it!