[basjoos]

The Schloerwagen has some interesting cabin vents installed in it. There is a little door scoop that pops open in the front just below the front windshield that lets air in. The other front air inlets are opened by warping inward the upper front corners of the two front side windows (next to the "A" pillars). I'm guessing these exhaust air from the top of the cabin. On the rear side windows, the upper front corners (next to the "C" pillars) are warped inward to allow air to escape from the back of the cabin. The glazing material was probably plexiglass (invented in the 1930's) as it is obviously flexible enough to be custom curved to match the shape of the car and to allow the corners to be bent inward an inch or two for venting purposes. Since this car was designed to be ultra low drag, I would expect the same care to have gone into designing the ventilation system to make its operation as low drag as possible.

If you look at the photo of the Schloerwagen with the propeller mounted in back, you can see it with all of these vents wide open. If you look at the photo showing the interior from the passenger's side door, you can see the clamps that warp open the upper corners of the front side windows. I suspect that downward facing handle just under the dash opens the front scoop vent.