Efficiency ideas are fine, however the more odd the car looks the more you will limit sales. The Volt, i3, and the Leaf are good examples of this. I think Tesla proved with the Model S that if there are no compromises, including the standard car look, that you can have a hit on your hands.
IMO the Gen III needs to be an elegant, expensive looking, yet reasonably priced mid-sized sedan and Tesla will sell 500K of them. If you make the car polarizing, then your sales will be polarized as well. Tesla needs a car that everyone will want to own. Everyone. Because of the smaller size it will already be more tricky to get as low a Cd as the Model S without compromising the looks. I have faith in Tesla and Franz to get it done though.
You can always go for unique efficiency extras as add-ons. They did drop the aero wheels for the Model S though...