[jakobnev]

There's an interesting paradox going on here: The car can be either wind- or ground powered depending on which inertial frame of reference we choose, but if we look at the mechanisms inside the car, then energy is always transferred from the wheels to the propeller.

Now the question is: How can that be? Shouldn't we see energy flowing in the other direction while we are standing on the ground and observing the car be wind powered?