Damn, I can get 6 gallons to last the weekend. I ride hard and for long sessions too. My guess is i dont have to ride to my spot since i launch from the beach. And since all we get around here is choppy surf, that helps too. On really clean days, that 6 gals will be gone in a day. yesterday i burned about 5. Waves were so fun, and it was pretty clean.
It all depends on the conditions for me.