[FiatLuxDave]

Yes, those little solar fans are pretty ineffective. Cracking the windows helps but is not as good as rolling them all down. I don't know of any cases of a child dying in a car with windows rolled down but I suppose it is possible. It is mainly children being left in sealed cars which results in fatalities.

I was thinking more like venting which was designed to use the temperature difference to pull air through the car, like the designs used in desert vernacular architecture. Maybe something like a miniature Persian windcatcher, or a vent in the roof and floor which open when the car is parked to allow convection through the interior. But really anything to make the car less like a sealed hotbox.