A little reverse engineering
 

We often speak about the perfect shape of vehicles for aero, like the aptera for example. What do you think would happen if we were to bellypan a 4x4, with the underside shape of drop. Meaning, round underbelly by the engine bay tapering to a point that meets up with the rear bumper. The upside down tear drop. Obviously for this to work the vehicle would have to have high ground clearance, but what if?

Tear drop shape works well in free air. Air is not free under car. Creating teardrop shape would produce a venturi that would cause the air to speed up relative to the car. Can't think of the space under a car same as space over it. Think in terms of a more effective duct shape. I.e. minimum surface air for the area of the duct and no sharp edges.

It would produce downforce at higher speeds. It may improve handling, but I think it would have a negative impact on FE.

But you could drive it right into the lake and go fishing with it ;)

I have to agree with the other guys. Underbelly should be smooth and flat.

reverse eng.
 

Dr.Michael Seal,of Western Washington University used a variation of what you speak of,with the university's Viking series of 100-mpg cars.The bellypan had a very long,upsweeping diffuser,and was designed for downforce as well as mpg.The diffuser did respect the 2-1/2 degree rule for the upswept portion.-------------------- The upper body of the cars were also very streamlined,hence the 100-mpg.

Hey, Bondo! Build one and try it with your cap!! :)

WHOA BABY! :thumbup:

http://vri.etec.wwu.edu/pictures/v23.jpg

oooh... yum... give that a turbo V6 getting 2mpg and I'd happily blast that monster around a race track. Give it an electric motor and I'd happily drive that slick machine to work or down the highway. Beautiful :)