There's nothing wrong with the idea of paying attention to function, ergonomics, economy of materials and a host of other concepts. But when theoretical ideals become a kind of perfection that must be sought at all costs, aesthetic sterility is an unintended, but likely, byproduct.
This function/form ideal has been most pronounced in the fields of architecture and industrial design, yet not so much where automobile styling is concerned. I think the reason is that a primary function of a car's appearance is to entice someone to buy it -- something quite different from mechanical or structural functionality. So the people in charge of studios dealing with the styling of production cars need to be commercially as well as aesthetically conscious even though some underlings might be functionalists of the purist industrial design stripe.
At times, the purists assert themselves and bland, blob-like cars enter dealer showrooms. Such was the case for certain General Motors products during the late 1990s. Yet to my thinking this was a faux functionality, a blend of aerodynamically efficient forms and elimination of ornamentation. Other functions such as location of the motor and space for carrying luggage were not starkly obvious (though most people, from experience, knew which parts of these cars related to such functions).
I draw the conclusion that aerodynamic functionality, in light of current regulations imposed on the automobile industry, trumps all other possibilities and therefore calls into question the purist possibility of designing a car that maximizes the form/function ideal.
Just for fun, what might an automobile look like if aerodynamic efficiency was set aside and remaining functions were stressed. Let's also leave out cars from the pioneering days when, for instance, the best placement of the motor was being sorted out by trial and error. If we consider cars designed and built from the early 1920s onward, my candidates for ultimate functional design are certain models of the Voisin brand, brainchild of French aviation pioneer Gabriel Voisin (1880-1973). In particular, I am thinking of his cars for 1931 and to some degree a few years earlier. Example images found on the Internet are shown below.
Voisin, a friend of the architect Le Corbusier (they were involved with the 1925 Plan Voisin for a redesigned Paris), must surely have been acquainted with the maxim "form follows function." So by the late 1920s his C14 line of cars visually stressed various functions to a virtually uncompromised degree.
Separately stated elements include: the passenger compartment; the engine compartment with the radiator at the front and the hood; fenders positioned close to the wheels so as to protect against splashes and road debris; storage boxes by the sides of the hood; running boards; a distinct luggage trunk; and the spare tire at the rear.
The Voisin C22 model carries the same theme, but with a more aggressive appearance resulting from its "underslung" chassis (axles and springs are above the chassis side rails rather than below, permitting a body riding closer to the ground). The effect is enhanced in the car shown here because it is a single-seat coupé body type and culminated thanks to the proportionally large diameter of the wheels.
More of the same is seen in this rare C20 model.