It could be interesting to find out how much it means in terms of range.
Someone with fibreglass skills should be able to make some custom covers
Just for the top half of the wheels (as that is where the wheel is moving the air at opposite the airflow, and thus double speed, quadruple resistance - roughly).
I even have an idea how all four wheels could be covered smoothly (top half or the two thirds upper part), while still allowing the front wheels to turn fully, although that would require a bit more work.
This would mainly be as an experiment - see how much you could actually gain.
On the lower half of the wheels, the wheel is spinning in the same direction as the relative air, so maybe just cover 1/2 to 2/3s of the wheels