[RedDevil]

So here is 4up. Same design as number 3, but slightly narrower and it now has 3 flaps with holes that fold over the antenna bolt, so by screwing that down both antenna and wing sleeve are fixed sturdily.


Again I folded the plastic back end like a double layered flat triangular box to create the wing shape and make the back end rigid.


It looks quite crude from the top, but down from that the shape improves to being just mildly crude.

So will it reduce the antanna's air resistance by 90%?
Who knows. I'd be happy with just 50%.

The force on the (unwinged) antenna is quite big at highway speeds. A 50% reduction in air resistance for the antenna might save 0.1% or 0.2% in total fuel usage.
The wing sleeve weighs almost nothing. The whole bagel box was just a few grams.
As the total cost was maybe just 1 cent for the glue I reckon this mod will have earned itself within the first tank full...!
Going for 100 mpg one tiny step at a time...