OK, let me just say I was a customer of Arnie's at Accutronics in Ann Arbor before he even started Audiogon. He and his assistant were selling used components out of the basement floor of the store on ebay.com; that worked pretty well, which is what gave him the idea.
I am out of the loop for knowledge on high end auto music systems
At one time I had also invested money and time in good stereo systems for good cars, but have been out of that market for too long. I would consider doing an upgrade to the stereo in an older used car I have, which is a '91 Porsche 944S2.
Where do you feel I should start on my info finding journey? Mainly for FM reception and multi cd (perhaps SACD} playback.