For fun I was doing some calculations last night. We could make it from
here to Jupiter Fl. with only one stop for fuel. The Navigator gets
thirsty every day on the same trip and it's fairly efficient.

Eisboch

You could realize somewhere around 4nmpg with the GB, not counting anything
burned in the genset for A/C or what not.

Probably what, 2-4 times better than the Navigator?