Paula,
The last extensive outing was Newfoundland and back. 91 days. Up and down some tough terrain there, and in Quebec's Eastern Townships and Maine.
Overall average, city and highway, up and down, was 18.32 miles per CANADIAN gallon. The Canadian gallon is larger than the US so the miles per gallon reading will be higher.
I Canadian gallon = 1.2 US gallon.
I don't know how to convert the MPG but somebody out there will.
The generator is in the Classifieds fine print. Japanese built SUBARU Robbins 4300 W:
Subaru Robin