The Elio fully enclosed reverse trike is currently slated for production and delivery in summer of 2014.
[EDIT]
As of Jan-Feb 2014 Elio is showing the P4 prototype which has improved aerodynamics. More details at
post #26 in this thread. Here's a photo:
[/EDIT]
Based on early photos I thought the body shell to be pretty slippery (not counting the outrigger front wheels). The newer photos here:
Elio Motors: Ultra High Mileage Car
show good views of rear quarter and from above. Click tab "Photos" and scroll down.
What do you think? Will the essentially flat rear deck lid cause turbulence?
How about the rounded back end? Is that worse than if they had continued the side taper to the same final total length, with a straight vertical back end?
[EDIT: Apparently Elio found they did hurt; the P4 version lost those drag-inducing features.]
Even so, I would not be surprised to learn this has a very low Cd and CdA.
I think one might build good tails for the front wheel fenders; I suspect they are the area with greatest trailing turbulence and drag.
I'm looking for comments from those here with a good education in fluid dynamics.