The gold standard for efficiency seems to be the whale, with a broad front end and tapering back end. Submarines have adopted it and airplanes have at least tapering rears.

But those little 4-wheel cars have square back ends. I'd think the airflow would create a negative pressure which would tend to slow the vehicle.

They're so competitive regards gas mileage that I can't believe they've overlooked it. Must be that the more or less wasted space would be too expensive to drag around.

Love the little cars. The Aptera actually seems to have possibilities, though it's about as roomy as a small general aviation plane.

Arf