Interesting thread. I saw this article at Autospeed for testing consideration:
We have a record! . I modified the intake on my wife's 08 Avenger a bit to feed more air to the engine, and I did see an MPG increase (sorry, I didn't know about ABA testing back then, but I can see an increase in the fuel logbook).
For the life of me, I cannot recall where I saw this, but someone has a Honda or Suzuki they modified the intake so that it was pulling air from the rain tray, with a piece of window screen and a sock or rag as the filter. Certainly extreme shade tree style, but it would let him take advantage of the pressure at the base of the windshield (like cowl induction). The pictures are: 1 grill w/hood popped--see small bump on bottom of hood; 2 factory intake scoop--red is where I cut open the side that was blocked; 3 factory intake still--red is where I cut into it and added a 2" PVC elbow to complete the blocked side as a viable intake (I tried to foam insulate but later figured that wasn't such a good idea); 4 raised hood with intake bulge clearly visible.
I previously owned a 91 Jetta. It had a plastic shroud around the right headlight to feed air to the intake, about one or two inches in front of the air filter box. Upon inspection, the air filter box had a snorkel inlet shrunk from 4" down to a 1" opening. I removed that and sealed the gap between the filter box and the shroud. Worth about 2 mpg and a bit of loud pedal.
Might provide you an idea...