I can't read in a motor vehicle that's moving. I get headaches in cars or buses when I attempt to read on them. I've always had this problem, I think I isolated it when I was seven or so. Oddly enough, this issue does not extend to trains. I can and do read extensively on the subway or the LIRR (when I lived in Massapequa). This is one of the main reasons why having music for my commute is so important to me. I can't concentrate on reading if there is music playing, though, so music is required only for the legs of the journey during which I can not read.
I am at a loss to understand what prompted me to make this a LiveJournal entry, but you've just read it, so now it is burned into your memories forever.