Bose are very overated and very overpriced the dolby prologic Josh is talking about is a casette noise reduction system and not proper pro logic... sorry to pwn you there josh....
Not strictly true, Dolby B, C and HX Pro are examples of Noise Reduction techniques.
Dolby Pro-Logic on the other hand, is actually a matrixed analogue 4.1 surround sound system. (Front Left, Front Right, Centre, Mono-surround, LFE)
The program material was "encoded" into any analogue Stereo source, eg. VHS video cassette, laserdisc , even NICAM stereo TV broadcasts.
It has the advantage of sounding 'normal' in stereo, and if one later upgraded to a matrix decoder, or a receiver with one built in, you could enjoy surround sound.
The system was originally known as 'Dolby Surround', but this had limited front-to-back seperation. Later, 'the pro-logic' part was introduced, with steering logic which improved the channel seperation.
It was eventually superceeded by Dolby Digital (sometimes known as AC-3), the system still in use today.
[ame]http://en.wikipedia.org/wiki/Dolby_Pro_Logic[/ame]
There were a handful of normal audio CD's produced using the Dolby Surround system
this is one of them :
http://www.wendycarlos.com/+sob2k.html
I'm assuming this is why Volvo included it on their ICE installs.
The Dolby Surround CD's obviously were a flop, though.