In a message dated 10/31/00 10:39:31 PM Pacific Standard Time,
andrew.grebneff@STONEBOW.OTAGO.AC.NZ writes:

<< A good idea would be to install a flush solar panel in the roof to power
 the ventilation fan automatically on hot days, to keep the interior cool. I
 believe the Mazda Luce (=929) has this feature. >>

I have one of these things except that it just hangs on one of the roll-up
windows. Solar powered. Fan draws air outward. The idea is it sucks air via
your existing airvents. Don't remember where I got it from but works great
here in California where unwelcome sunlight can bake Vanagon interiors.

BenT