William Ames Bacon has this article in the WSJ describing the day he sat in on his brother's class at Harvard Law School.

Prof. Mansfield (who died in 2014), told a story about two guys driving a hearse from Maine down to Boston late one winter's night to deliver a corpse for a funeral the next morning. The guy who was riding shotgun dozed off about 11. A little while later the driver, who was also beginning to nod, pulled over at a Howard Johnson's to get some coffee for both of them. When he came out, snow had started to fall, and there was a guy with a duffel bag standing beside the hearse. He asked the driver if he could catch a lift to Boston. "Sure," the driver told him, "if you don't mind riding in the back with the deceased." The stranger didn't mind, and he climbed into the coffin compartment through the wide back door, glad to be out of the cold. The driver, deciding it was his partner's turn behind the wheel, woke him up and gave him the extra cup of coffee.

About 2 a.m., the threesome (foursome if you include the deceased) was nearing Newburyport north of the city. That was when the passenger in the back woke up and reached through the velvet curtain separating the coffin compartment from the front seat. He tapped the driver softly on the shoulder and whispered, "How much farther to Boston?"

It was at this point the guy who had taken over the driving at the Howard Johnson's screamed in terror and swerved the car off U.S. Highway 1, plunging into a snow bank.

In Air Force flight training, they drilled into us the importance of crew coordination.  I gather that hearse drivers did not receive equivalent training, at least in those days.