[RedDevil]

The car should work for a whole variety of parameters, so he can take an educated guess at anything he wants to calculate about - just as long as everything meets the following criteria:

- The car moves downwind,
- The propeller pushes the air back more slowly than the car moves over the ground,
- The wind puts a positive force on the propeller and
- The car forces the wheels to turn over the ground, driving the propeller.

While the propeller pushes the air backwards compared to the car, it still moves forward compared to the ground, just slower than the wind.
Therefore the wind does put pressure on the propeller, thrusting the car forward.

When the car is not accelerating the force on the propeller and the wheels is roughly equal, but the wheels are moving over a greater distance than the air moves through the propeller, so less power is required to turn the propeller against the wind than the wheels provide.

Just pick some reasonable numbers for anything you want. It will work.

No need to wait until the make of the propeller, the viscosity of the oil in the bearings, the weight of the driver and the humidity of the air are determined and verified by an army of lawyers.
If you see how it works you'll understand none of that is necessary.

Keep it simple. Don't drag in all sorts of data that you really don't need.