Lot's of factors will affect gas mileage....carb maintenance, gas quality, winds, engine temp, speeds, etc. My best fuel consumption was 52 mpg (avg 45 mph), worst 34 mpg (lots of twisting the wrist ), currently avg'ing 44 mpg (avg 65 mph). I average around 240 miles between fill-ups....not using reserve.
FWIW: I put in an ounce of fuel stabilizer on each fill-up and run 2 ounces of Sea Form through the system about every 2500 miles. Although some on the Forum may frown on using Sea Form; it has worked fine for me in all my engines...lawn equipment to automobiles!