I looked it up (
http://www.marklevinsonlexus.com/levinsonforcarsd.html), and it appears to be two channel audio only. If multichannel audio was implemented, I am pretty sure the site would have made sure to mention it.
It is very easy to outfit a car for multichannel audio that makes use of Dolby Digital and DTS sound formats.
I think perhaps you are thinking about a different car brand. Current Acura TL's support DVD-Audio and DTS.