The car issue is the biggest thing holding me back from Hi-MD or any other new solution. I have been a big MD fan for 9 years and have always had one in the car, where I listen to the most music. I currently have Net-MD and if I upgrade to Hi-MD, I won't be able to listen to the discs in the car. Either that or I will have to keep separate discs for the car and for everything else, which will be a pain.
I guess I could try to find an old cassette deck for the car and go the cable route again. I got an answer from Sony that their priority is not on the car unit at the moment, so I doubt one will ever come out. I guess some companies are coming out with Ipod solutions for the car, though...