basjoos, 100 mpg is just wonderful. Your car is like a flying needle.
From what you wrote about your front design, I'm considering a further mod to my front. Not a complete horizontal wedge like yours, it's just toooo radical for me at this point.
I'm considering a complete flat near-solid "grill" replacement going across from corner lens to corner lens. Lower edge will be even with bumper's top forward edge and the upper edge will meet the hood. So it's about a foot tall, and has an angle of maybe 30 degrees off vertical. Will have cutouts for the two headlights (each 6"x8") and the radiator + air intake.
Hmm. I could extend the lower edge further forward than the bumper. Would wreck under impact but... the slope angle would change for the better, considerably.
Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.