Someone posted this idea on PP a few years ago. I always thought that it was a clever concept, but never did anything about it. Today I came across some junk pieces of 2" plastic drain pipe and the thing popped back into mind. So, I made this:
Two pieces of pipe of arbitrary length are installed into a 90 degree elbow (maybe you don't even need the horizontal piece, but that is the way the original was constructed), and I cut a slot into the piece that projects into the car.
I made the slot just wide enough so that it is a very snug fit over the glass. Press the 'air conditioner' onto the glass where you want it and roll up the window. You can cut the angle of the slot so that the pipe blows air at the height you like.
My car is plenty hot without any air conditioning, and the ventilation is otherwise poor, unless you open the windows fully - which is not as effective as I had hoped for. This simple pipe gadget is fairly unobtrusive, and it really blasts you with air at highway speed. I found that I enjoyed my car more, because I could remain cool without the noise and diminished aerodynamics of fully open windows.
It was a warm day for this location (28C, or low 80sF), but I was totally comfortable, whereas I would have been much hotter without this invention. I agree, it is somewhat peculiar, but the success of it makes me ignore this completely.
Who is the bright person who deserves credit for thinking this up? It works very well. It makes a small amount of noise, because the air blows through it at a speed roughly equal to your road speed. It's worth it.