Form follows aero function (no aesthetics) for Ferrari and Lamborghini cars
 

If Ferrari and Lamborghini only focused on low drag and downforce their cars would look like this

http://s27.postimg.org/rc4d64zdv/functional_shape.jpg

This would allow low drag while still having room for downforce generating venturi tunnels
http://s28.postimg.org/geiex18lp/basic_catamaran.gif

They make a big tradeoff for aesthetics so their cars look quite different from the depicted model.

catamaran
 

Honda R&D investigated the catamaran body with their Dream solar car series.I don't have the source with me,but my failing memory tells me that their 1996 Japanese Society of Automotive Engineers paper claimed that the catamaran generated about 20% higher drag than the 'pumpkin seed'/'flattened-torpedo' body.
Here is one of the bodies they chose for competition,which won the World Solar Challenge.It has Cd 0.10.
http://i1271.photobucket.com/albums/...Untitled17.jpg

Cross-winds. It's sort of an anti-Morelli.

Solar contest cars tend to focus on low drag, at lower speeds, with minimal creature comforts. A high performance sports car is focused on down force and visual impact. The catamaran shape is approximated with individual wheel fairing and belly pan designs. Road conditions require a certain amount of ground clearance. Cars that require the driver to be uncomfortable getting in or out would not sell. Side curvature and down force are used to minimize cross wind effects.

http://ecomodder.com/forum/member-fr...wu5wo1-500.jpg

Luigi Colani demonstrated downforce without a separate wing.

An LMP1 or a Formula racer is the ideal shape that supercar makers will always try to approach or approximate... though they'll never make the cars that ungodly uncomfortable.

The ultimate expression of this is the T1 Caparo...
http://www.autoblog.nl/gallery/Capar...aparo_T1_1.jpg
Which is, visibly, a terrible design, drag-wise.

More realistically, they'll end up with a design and packaging similar to the McLaren F1, which was probably the last road car to become a successful top-level racing car. Low drag is nice, but the need for cornering stability, suspension travel, wider tires, engine cooling, a low center of gravity and etcetera, are always going to push the cars into similar shapes.

Aesthetics, dynamic performance, cooling, Centre of Gravity... The list goes on.

Case in point is any car that targets the mass-production high speed record. Why don't they use that low-drag design? Because the power needed to reach those speeds also required a huge amount of cooling. Something that really dogged the Bugatti Veyron throughout its development. You also have to make it a perform at all speeds upto that max speed, so that's low centre of mass, suspension geometry and downforce.

function
 

Here is a 1967 Ferrari 330 P4 (upper image)
http://i1271.photobucket.com/albums/...ntitled7-3.jpg
And 1995 Ferrari F355 Berlinetta
http://i1271.photobucket.com/albums/...ntitled3-5.jpg
Lamborghini Countach of the 1980s
http://i1271.photobucket.com/albums/...d2/06-2823.jpg
and Lamborghini Aventador LP 700-4 of 2011
http://i1271.photobucket.com/albums/...Untitled22.jpg

The rear angle of the Countach is good, but all those vents and scoops take their toll, like .40cd :eek:

.42 for the Countach, but I believe that is without the wheel flares and rear wing.
Those probably* brought it closer to .50 or more.

Here is an original tuft test without the wheel flares and wing. Also, note the intakes along the sides were flush, unlike the later versions.

http://us1.webpublications.com.au/st...0/3058_8lo.jpg

later version : http://1.bp.blogspot.com/--3OfYL9GVR...+Countach1.jpg

My favorite bit on that car was the aircraft inspired NACA duct .

* new lazy wordage : " prolly, or proly"