Belly Pan / Under Carriage Cover anyone ?

[JimKellyfan]

Having worked on many models, and of course the changing times, you see differences. Like the Prius and it's mileage gains (as well as other models and makes).
-You see the feather light rims.
-You see the headlamp (where it meets bumper) is tucked under the bumper at the front
You see underpinnings/belly pan/undercarriage covers, especially on the Prius and Fusions, as well as others. (my 10 has small beginnings of what the Prius has)
Of course the aero body isn't the only thing saving fuel, it's the other tech stuff too like direct injection with no fuel return in a sealed environment, tighter and more gears, and so on.
----Has anyone found belly pans on the newer Yarii ?
----Has anyone made one up or used one from another vehicle that would fit from the Yota family ?
Just curious, but I think that would help squeak some more miles per gallon out on the highway.
Body gap trim would be another idea, but I would think a belly pan that is usable, and wouldn't over heat the engine or trans would be a good thing for mileage.
Thoughts ?