The film, written and directed by, and starring Thornton, features two families brought together by the death of their matriarch.
Thornton, Duvall and Kevin Bacon play the Southern half of the family, welcoming Brits John Hurt and Frances O'Connor, who are bringing the body of the dead matriarch to be buried in Alabama.
The film marks Thorntons first return to writing and directing since 2001's "Daddy and Them." He also won an Oscar for writing "Sling Blade" in 1996.
"You don't want to do it until you have something that you really want to do that is personal to you," Thornton told Yahoo of returning to the director's chair. "You get busy as an actor, and that's predominately what I am, is an actor."
"Jayne Mansfield's Car" will be available on-demand beginning Aug. 20 and will hit theaters Sept. 13.