A lot of words and no equations.
Well, it is better than unphysical nonsense and equations unrelated to the physical phenomena at hand. You seem to believe that if an equation applies in some specific situation, it must apply always, and that just isn't so.
Like I explained, if a vehicle uses the fixed ground instead of surrounding air in its propulsion mechanism, the amount of energy it can obtain from wind is not relative to the vehicle speed, it is relative to the ground. So no subtracting vehicle speed from the wind speed relative to ground.
Extracting the energy is only an engineering problem.
Because of the
Venturi effect, the exact wind speed just isn't an issue wrt. harvesting energy from it.
You insist on using static surfaces, ignoring all pressure-related effects, as if the vehicle is and has to be a simple rectangular box, with no internal mechanisms and only interacting with its environment via elastic collisions. It is silly, and quite annoying.
You need to move past your preconceptions. For example, you could start gently, and consider a vehicle with a very aerodynamic shape, say saucer-shape with a sharp edge, with upper and lower curvatures different (to balance out any vertical forces, including lift, due to the pressure differential), and with a
Gorlov helical turbine poking up on top. It has minimal drag, and the turbine efficiency is about 35%. It typically operates at tip speed ratio over 1, which means that the induced flow rate due to rotation of the turbine is greater than the flow rate with respect to the axis. Go read
Gorlov's 2001 paper on it, but do recall that it only considers the properties of a stationary turbine.
And before you assert it, no, a moving turbine is not the same thing as stationary turbine in zero-wind situation. It only matches if we assume the turbine is not moving in either case, and that's not going to happen with a moving turbine. Because of the tip speed ratio being over 1, even when the wind speed approaches zero relative to the turbine axis, the turbine isn't going to stop (unless it has bad bearings or other significant losses). Because it can keep accelerating the vehicle all the way, it will be less efficient at that particular point compared to speeds immediately above and below, but it isn't zero even there.
What makes that seemingly simple construction interesting, is the fact that airflow speed varies as a distance from static surfaces like the ground, below the
boundary layer. This means that along the vertical turbine axis, there is always a range of wind speeds relative to the axis, and because the wind direction does not affect the turbine, it can extract energy from the wind even when the vehicle is traveling downwind at the nominal wind speed. This applies even to wind tunnels (and in those, it is most noticeable, because they have laminar flow patterns by design; in nature, wind tends to be a bit turbulent). That sort of a vehicle does not even need wheels, it can even use a propeller for the propulsion, as long as it keeps close to a static surface (ground), and still achieve faster than nominal wind speed downwind or upwind.
When you wrap your mind around that, go look at aerodynamics, propulsion, and so on, and expand your understanding from there. Reconsider the models and practical examples I've shown earlier in this thread. Don't get stuck in your preconceived notions just because you're emotionally heavily invested in them. Learn to entertain ideas and theories and models that you do not believe are true, and learn how to rationally examine why your beliefs and the idea/theory/model do not agree.