[Leonard] Bernstein came from a family of Talmudic scholars, but was only moderately observant in his adult years. However, Bernstein would hire a taxicab for Yom Kippur and go around Manhattan “shul-hopping.” He did this because he loved to hear many different cantors’ interpretations of the traditional prayers.
Bernstein knew, of course, that riding was forbidden on the holiday, so he would have the cab driver drop him off a block away from each synagogue so that synagogue-goers would not see the famous conductor riding on the holiday.
—Jewish World Review, October 10, 2005
Caveat: A morning in the library hasn’t turned up corroboration of this story, even by Joan Peyser, who presumably would have jumped on it like a Pomeranian on a meatball. Sounds like Lenny, though.