Len, I'm in no postion to argue with an audiologist, but the last time I checked, the first (lowest) 14 keys on a piano produce a frequency of below 60hz, with the lowest being 27.5, and I'm pretty sure that the last time I had a tinkle (so to speak) I could clearly hear them all.
As for the stereo thing, yes, in car hifi is a compromise, but I can assure you that I get a very good stereo image in my mk2. Tweeter placement is one of the most important things to get right, because this is where most of the higher frequencies occur, and are most detecable from a directional point of view. People who take SQ installs very seriously often position the tweets half way up the A pillars.
Obviously, the seating position is not ideal, but again, you can compensate for this by using time alignment. The point I'm trying to make is that with well positioned front components, you will get a pretty good sound stage, because even though you are off centre, you are still sitting between the speakers. With rear shelf mounted speakers, you'll just get sound, with much of the detail lost before it gets to you.
