The hearse is the transportation of Vincent Van Ghoul.
Scooby-Doo! Mystery Incorporated
Van Ghoul personally came to Shaggy Rogers's home to tell him he won a contest to eat dinner with him. He then drove Shaggy and Scooby-Doo to his mansion, with Shaggy and Scooby in the back because there wasn't enough room in the front for both of them.