Fuel economy could be fuel consumption vs unit distance, or unit time.
If it is per unit time, you don't care where you are going (yes, could be hovering), and thus winds and groundspeed are not important. All you wanted was the longest time off earth, thus the least fuel burn per unit time, which will be achieved at an airspeed of best endurance. Any faster airspeed, and you're burning more fuel than you need to to simply stay aloft, any slower, and you're burning more fuel to overcome increasing induced drag. Winds and groundspeed don't have a place in those equasions that I can see.
If getting somewhere is entering the equasion, than it's an airspeed for best range, and that's fuel consumption per unit distance. Now wind and groundspeed play a vital role in the equasion...
Pilot DAR