Judd Apatow, who regarded the late comic master Garry Shandling as a mentor, produced and directed this documentary — adding interviews with comics who knew Garry and worked with him (Sarah Silverman, Jim Carrey) to vintage Shandling stand-up, “The Larry Sanders Show” clips and that last, memorable “Comedians in Cars Getting Coffee” appearance.

The film focuses on the good and the bad of Garry, whose “You’re dead to me” behavior to those who crossed him was legendary, whose quick wit was hard to match.

Shandling looked deathly ill, but sitting in a 1979 Porsche 930 (Seinfeld’s personal brand), riffing on life, comedy, spirituality, the man delivered one of the great live (on tape) epitaphs in comedy history.

“Zen” premieres tonight on HBO.