The daughter of an Oscar-winning Hollywood director has been found dead inside a vehicle parked on the side of a busy highway.

Judith “Judy” Wyler Sheldon and her husband Wylie Sheldon were found unresponsive in their running Jeep Compass on Interstate 5 in California in the US on Monday afternoon.

Judy, 84, was the daughter of legendary filmmaker William Wyler, whose classics included Roman Holiday, Ben-Hur and Wuthering Heights.

California Highway Patrol officers made the grim discovery after coming across the vehicle stopped on the shoulder of the highway.

Emergency crews rushed to the scene but despite desperate efforts to revive the couple, they were pronounced dead at the scene.

Authorities said that Judy was behind the wheel when she was found, with Wylie, 86, in the front passenger seat.

Their causes of death have not yet been released.

The deaths came on the same day an extreme heat warning was issued across parts of Northern California, although investigators have not said whether the scorching conditions played a role.

While her father became one of Hollywood’s most celebrated directors with three Academy Awards, Judy forged her own career in the movie world and was a passionate supporter of silent cinema.

Friends paid tribute to the couple after the shocking discovery.

“We are reeling from this news,” San Francisco Silent Film Festival artistic director Anita Monga said.

“Judy and Wylie were very dear to us, supportive and a positive presence at all our events.”