The angle of attack of the propeller blades and the gearing relative to the wheels cause the blades to be seen by the wind as moving upwind relative to the grou

The angle of attack of the propeller blades and the gearing relative to the wheels cause the blades to be seen by the wind as moving upwind relative to the ground. Alternatively, think of it as merely harvesting energy from the velocity difference between the ground and the air. It's connected to the ground by wheels, and to the air by a big prop. It doesn't matter how fast the vehicle itself is moving as long as the gearing is right. Ultimately, the top speed is limited to when the friction the vehicle encounters from drivetrain losses and aero drag exceeds the power it can extract from the wind/ground speed difference.