Susan Sarandon as Mom Racer.It was after the 1968 Democratic convention and there was a casting call for a film with several roles for the kind of young people who had disrupted the convention.
Two recent graduates of Catholic University in Washington DC, went to the audition in New York for Joe (1970). Chris Sarandon, who had studied to be an actor, was passed over. His wife Susan got a major role. [ source:imdb ]