Expect about 16 mpg, 350 mile practical range. About the same as my E-450, 8 mpg on 55 gallon tank that needs refill at 35-40 to keep. genset running. Better than my Fit getting 36 mpg on 10 gallon tank I fill between 8 and 9 on trips, or daughter's Odyssey getting 20 mpg and hitting "empty" like at 16 gallons used.
Not quite as much range as larger motorhomes getting 6-8 mpg on 75 to 100 gallon tanks, on those few compact cars and crossover SUVs with 30 mpg 4 cyl engines, equipped with fuel tanks to feed the hungrier V-6 they used to have.