The below article actually makes some good points on variations we report between high end car specific designed systems. I does INCORRECTLY state the RL and TL systems are ELS. RL is BOSE.

http://www.latimes.com/news/printedi...news-highway_1

I did like this excerpt:

The best sound systems on the road — found in the Acura RL and TL — use active noise cancellation, a technology that produces signals 180 degrees out of phase with the background noise, cutting down aural clutter. Bose, which pioneered the technology, is putting it into its own high-end OEM systems.