Well, I agree with the Holy Cow, I'm not crazy about the way they look. But I guess they may be worth leaving on from the sounds of it. I'm not sure I could take them off without breaking them, and I'm definitely not sure how I would put them back on if I wanted to.
I guess I have bigger fish to fry, i.e. a ScanGauge, grill block and injector cut switch. And tires that don't leak.
...and I have a LOT to learn about urban hypermiling.
I know for Honda's, they are quite easy to put on and take off. They just slide in between the plastic on top where the glass goes in. You put them in exactly the same. Just flex it a little in the middle and pull it out from one side.
I find these to be pretty convenient on hot days where worrying about getting your seats wet is no issue. They also work well if you're smoker.
my father's pickup (1970) has the vent windows, my cherokee had them, and i wish my beetle had them. i get some of the same effect with the sunroof in the popped position, but it's just not the same.
and those vent things, dang they're expensive for my car, $75