Well yes but generally speaking a bike gets relatively poor fuel milage. Much less weight, much smaller tire patch, arguably less width and height so less resistance, smaller engines and still not a huge difference in milage.
IE: My Audi A8, full size 300 hp, not sure about weight but I can't pick it up if it falls over, gets 23 - 24 mpg. The bird, 45-46 so twice the milage but it's not half weight of the car.
Half the hp yes.