Solar-Powered Car Vents - A Lot of Hot Air?

I’m not a big fan of cars, but years ago went to live in a small, rural village with limited transport options, so ended up with a compact hatch. Excellent fuel economy, but lacking niceties like air conditioning. And it’s not uncommon in the height of an Australian summer for the temps to hover around 40oC (104oF). A closed car interior left sitting in the sun in these conditions can easily turn into a furnace. (I’ve had to wear gloves, on occasion, just to hold the steering wheel!) In a new car this oven effect can increase the levels of nasty VOCs being emitting from the phthalates in the ever abundant plastic trim and fittings. Aeons ago I spied little vents, like those pictured above, and wondered if they might be a partial solution to the dilemma. You perch them atop a door window, face the solar panel outwards and wind the window up tight. The small photovoltaic cell powers a fan, which is said to expel the hot glasshouse-type air from within the car, drawing in cooler air. But I’m yet to try one. Has any TreeHugger used these gadgets? Do they work? Would be a great way for cars to reduce air conditioning use, thus increasing fuel economy, if they did. ::Digital Kitchen, via CNET.