Of course everyone will have an opinion as to if and how important this issue is.
For me I will never ever ever understand why anyone could care about fuel consumption on a 412kw car.
If you value that so much buy a 4cylinder diesel or a Prius.
Each to their own.
Porsche 991 911 Carrera S
BMW F10 M5
BMW F15 X5 5.0 Xdrive M Sport.
Mazda CX5 GT Diesel.