We all have bad milage if you compare to what ads promise. Live in mountain area and hav 6½ L / 100km. Comparing to what Lexus did claim when we bought the car 3.8L/100km it is pretty bad.
All companies tell us we can drive longer on a full tank than possible in real life. Not just Lexus.
ECO or normal mode is different. If you press pedals hard in ECO you use more gas than when doing it in normal mode.
Talking about miles and gallons is difficult to me as there are more than 3 different lenght of miles (I know Sweden, UK and US at least) and gallons are not same all over the world, maybe not even same all over US.