IMHO, the only reason for going through the troubles of having an A600 instead of a 100-150 EUR Car CD/Mp3-player that fits nicely in the dash (150 EUR will get you brand name stuff, and you'll need something to hook the Amiga up to anyway in order to get sound in the speakers), is the good old 'because it's an Amiga/because it's possible'
But he's done a good job, though, except for the cassette adapter thingy, It kinda ruins the look...
Well, that's my opinion anyway.