Solar powered car fans

As long as we’re doing the “car color” thread.

Do those little solar powered fan gadgets to stick in your car window while you’re parked in the sun do anything detectable? Offhand, it doesn’t seem to me that a dinky little plastic fan run by a dinky little solar cell is going to move enough air to make a difference. Has anybody here been curious enough to spend $14.95 to find out?

Can you switch them to blow air out instead of drawing it in? It would seem that you would want to arrange a couple like the muffin fans in your computer case, with one on one side of the car drawing air in, and one on the other side blowing it out.