If we have a catastrophic natural disaster in the US, we won't run into this problem

That doesn't work because we have catastrophic artificial problems.

We all accept that this vehicle derives it's motion through the rotation of the propeller which drives the wheels.

No, the wheels drive the propeller. The wind still pushes against the propeller, and that's what pushes the car forward, but some of the energy is taken back from the wheels to turn the propeller and blow air backwards. The result is an addition to the wind speed. Alternatively, you can think of the propeller as part of the car that is going enough slower than the car that the wind can still push on it even if the car is going faster than the wind.

I used four rubber stoppers and a six-inch metal rod. Two stoppers were #10's, and two were #5's. I pushed the #5's onto the rod first so they met in the middle of the rod with the big ends almost touching. I put the #10's on the ends of the rod with the big ends on the outside. The result was an axle with two big wheels at the ends and two smaller wheels near the middle. I set it on the table, then I slid a ruler under the small wheels and pressed upward lightly. The big wheels touch the table top, the small wheels touch the ruler. Move the ruler back and forth in the rolling direction, and presto: The contraption rolls in the direction of ruler motion, but at a faster speed. Having aerodynamics involved makes analysis much harder, but I'm beginning to think that the described wind car might really work.