The Ferrari is not really all that aerodynamic. The sleekness is for looks more than lack of wind resistance. Just check out the wheels, which would cause a lot of turbulance whipping through air. What little attention they do give to the windstream is used is to push downwards at extremely high speeds so the car can hop over a hill without going airborn.
The key design feature of a car like this is "overkill". They don't care about fuel efficiency. They simply live in dread fear that someone in a Porche might be able to pass them on the Autoban. That's why they use 12 cylinders to power a car that woud do well with four, hence the single digit mpg.
Imagine you are an air molecule. An Insight whips by you, shoving you out of the way, then it is gone. You got shoved once by that teardrop shape along the side, or maybe twice if you went over the hood and then against the windshield. The energy it took to push you one way, then return is the energy consumed for the car to pass. Now, imagine you get passed by a Ferrari. All those fake and real scoops and fins and those sexy curves going in and out mean you get yanked around several times before the car passes, first pushed out as the nose shoves you out of the way, then pulled back in when a curve, fin, scoop or other feature sucks at you, then shoved back out when the next feature is in the way, then sucked back in, and then finally, you get sucked back toward that big, blank tail of the car. A lot more energy gets consumed, even if the car DOES look sleek.
Another way to think of it (Relativity is great for this stuff) is that every bulge or protrusion has a standing pressure wave in front of it and a standing vaccuum behind it. Pressure waves in front of a shape hold it back. Vaccuum behind a shape holds it back, too. Put a ball or a cube or any other simple geometric shape in a windstream and the pressure waves will form something close to a teardrop shape, with some turbulence at the tip of the tail.
Wind tunnel tests show that if the object itself is shaped like that teardrop, the object slides easier through the air, and if you snip off the tail where the turbulence is, there is no noticable gain of wind resistance. That's how the Insight got its snipped teardrop shape. The need for a reasonably priced windshield is one of the few compromises to that smooth teardrop shape. Also, give it the total teardrop shape without the distinctive windshield and the car becomes a butt ugly 1940s sci-fi fantasy vehicle.
