I see your point, but in NA it's common to use US gal for everything, not the imperial gallon. Look at the data for fuel use coming from any leading US boat manufacture it's all MPG (us gal).
Not saying you are wrong at all, but it gives the impression of an inflated MPG if using the imperial gallon conversion so it should be noted so everyone is talking apples to apples as we get lazy and call it "MPG" for both imperial and US gal. End of the day lots of different ways to illustrate the distance traveled per unit of fuel. Sounds like Derby likes using L/Mi and he likes that.
I have always been an MPG guy for boats, but it all works
As for the G2 those are good numbers. How much oil does it burn in 100 hours?