What is the seat behind the passenger seat called?

The cushion where the driver or passenger sits on is either called a horizontal cushion or seat cushion. The back of the car seat (No. 16) is called the seat back but it can also be referred to as a backrest.

What is a 6 way power driver seat?

Six way power seats are designed to allow wheelchair users to tranfer from the back of a van into one of the front seats. They move foward and backward, rotate towards the center of the van and back facing the front and rise and lower as needed. All functions of the 6 way seat are done electrically.