A scooter is more fuel efficient then a sport bike but the scooter has hardly the power of a sport bike.
This depends on how you define "efficient."
The goal of any technology is to perform work. In the case of an engine, the work entails moving you around from place to place.
Power is the time rate at which work is done or energy is transferred,
where P is power, W is work and t is time.
In mechanics, the work done on an object is related to the forces acting on it by
where F is force, and Δd is the displacement of the object.
When it really comes down to it, the powerful sport bike is more efficient than the piece of #$%* scooter; it does much more work at a much higher rate of speed per unit of energy input.
In more practical terms, take the sports bike and drive it around as if it were a scooter. In other words, stay below 50mph and accelerate as if you had 5 available horsepower. I'm willing to bet the sport bike would get better mileage than the #$%*ty scooter.