“For what you claim to work would require “still” air to drop in temperature aa you move the pinwheel through it.”
Not true, because since you’re moving the pinwheel through the air (assuming it’s not freewheeling and therefore having no effect on the air), the pinwheel blades are speeding up the air molecules. By ‘speeding up’ I mean the molecules are moving faster coming out of the blades than going into the blades.
So the temperature of the air coming out of the blades is higher than the temperature going into the blades. This is the case when the blades are moved through the air, as opposed to the air moving against stationary blades.
When moving air is deflected by stationary blades, the air is slowed down.
You believe a 20 mph wind blowing against a stationary pinwheel would have a different effect than still air and a pinwheel held out the window of the car traveling 20 mph?