The spinners only look like they're spinning when the car comes to a stop. When the car is driving, the wheel and spinner would be rotating at nearly the same speed.
If you are dedicated to making this work, you could make something similar to an anemometer or a shallow VAWT on the spinner so it rotates in the opposite direction from the wheel.
If you apply a load to the coils, such as charging a battery, either the spinner will stop regardless of wind while creating drag because the VAWT is so small, or it will generate a tiny amount of watts while creating drag.
It would work, but it would add complexity, weight, and cost to each wheel that was configured this way, in exchange for a tiny benefit. If the stator was on the wheel, you'd have to get the electricity to the battery through brushes.
Another bad idea that might be slightly better, would be to add magnets to the inside of the rear wheels and mount a stator onto the rear brakes, no brushes that way.
Regen isnt very productive because batteries can't absorb all the available power coming back when a hybrid is slowing down, but the hybrids all have it because "every little bit helps". There is some work going on with paralleling large capacitors with the battery, to absorb more the regen.
Slowing down is typically much less than 10% of a trip on average, so regen will never be a huge benefit.
Putting anything into the wind off of a car to capture some energy adds so much drag and losses, several electric vehicles have used a gasoline-powered generator on a aero-trailer to add range on occasional long trips.
There's a lot of experience using regen on electric scooters, but the major benefit seems to be the brakes last a very long time. On electric bicycles, the vehicle is so light, regen can lock up the wheels, so E-bike regen is usually adjustable (also meaning even less regen gets back into the battery).
