i'll throw in a data point... i just did some math last fill up.
60oz, 28.8mi (two round trips to work and back).
60oz/(128oz/g) = 0.46875g
28.8mi/0.46875g = 61.44mpg
no long stretches, and i tend to use my throttle like an on off switch (in other words, i'm either holeshotting wide open or grabbing brakes).
for reference: 64cc polini kit on yama chappy with vm20, 13t front 30t rear (7% taller than stock 13/32), flat ground top speed 47ish mph.
i think i could squeeze another 10, maybe even 20 mpg out of it if i demonstrated some throttle control and i was doing longer stretches of highway. another 40? not gonna happen imo.