I remember in Coe's biography, that during his buildup for Moscow he was running 80mi./week. So if he did not count warmups and had 2-3 hard sessions with 2mi warm up and warm down we are talking about 88-92mi./wk. What he did before 1984 one has to remember that he was coming back from a serious illness so he probably could not do as high of volume as he did in the past.
However he did it obviously it takes hardwork and there are no shortcuts.