I'm 1,82m tall (or short for my Swedish friends )and with 18 way seat I have a lot of space for the legs of passengers in the rear seats. If I remember correctly the back of the seat (in the lowest area) is quite the same between 14 and 18 ways.
Exclusive shot of @Diego at the wheel, leaving tons of space behind him.
Joke aside, I’m just shy of 1m80 myself and I can seat very comfortably on the back seat without moving the 14/18 driver seat, with several inches of space in front of my knees.