So the power required to fly at any given airspeed is equal to the drag multiplied by the distance flown through the air divided by the time taken.
Keith, you've confused air miles and ground miles. Power required should be measured in this case as numbers of molecules of air being flown-through, not nautical miles flown over the ground.
My understanding is that the V in the drag formula is velocity with respect to the air the aircraft is in, ie IAS, not TAS.
The power required at Seal levl and FL300 for the same IAS is roughly the same.