Jolissa and her car needn't be together anymore.
Maybe Jolissa is indeed in Avocado lake, but without the car. AWP specializes in underwater searches for people in cars. In fact, they started out with locating cars and other items underwater for fun and for environmental reasons. When they found a car with human remains in it, they changed the focus of the group and took it from there.
The way they search with live scope and magnets for instance, well you cannot use a magnet on human remains, only on metal like parts of a car.
IMO if Jolissa is in Avocado Lake, she is without her car, because the car returned apparently to town according to LE. It is not clear to me if it was indeed Jolissa in the car.