So to clarify;
What does a GT get l/100kms
What does a 3.0 get l/100kms.
Worst way of judging a car.. you'll never get true figures, as everyone drives differently.
What the book says the car will do, you will NEVER achieve.
put it this way, I average 380k's per tank on the GT the way I drive.. and I emphasise "I drive", as we are all different, and drive different paths and locations.