The Pebble Beach Concours d'Elegance is the type of car show that draws serious Ferrari shoppers every year. Held at one of America's most prestigious golf courses, the event draws high-end show cars and well-heeled spectators. Ferrari took advantage of the surroundings to display its regular production vehicles and a pair of one-off "concept" cars at the 2006 Concours, held Aug. 20.

The difference between the concepts Ferrari showed at the Concours and those you might see at the Detroit Auto Show, for instance, is that these cars will most certainly never see regular production. That's because they were designed specifically for private owners using existing Ferraris. The "Kappa" is a reskinned 612 Scaglietti coupe, and the "P4/5" is a revamped Enzo supercar.

A hood scoop is among the subtle differences between the Ferrari Kappa concept (top left) and its 612 Scaglietti (top right) parent. The Ferrari P4/5 concept (bottom left) is based on the Enzo (bottom right) but has all-new sheetmetal.

While Ferrari offers clients a range of personalization options, such as custom interior and exterior colors, Kappa and P4/5 take this idea to a different level. Both cars received their designs courtesy of Italian coachbuilder Pininfarina. The firm has also penned such cars as the Ferrari F40 and Maserati Quattroporte. Both Kappa and P4/5 have retained the basic mechanical components (engine, transmission) of their production counterparts.

New York Ferrari collector Peter Kalikow owns Kappa. Pininfarina's task was to reskin his 612 Scaglietti. The sheetmetal is all new, but Kalikow mandated the design be done in such a way that only the most passionate Ferrari enthusiasts would recognize the changes. The most glaring change is the addition of a large hood scoop. Also redone is the rear end, with taillamps from the Enzo. A slightly revised egg crate grille and lateral air outlet round out Kappa's more subtle changes.

Another New Yorker, James Glickenhaus, owns the one-of-a-kind P4/5. Not content with the exterior appearance of his personal Enzo, he worked extensively with Pininfarina to bring P4/5 to life.

This concept draws heavily on Ferrari's racing heritage. Many of the lines are reminiscent of the 1967 P3/4 race car. Pininfarina engineered P4/5 with unique 20-inch tires and wheels, and the firm also put the car through a wind tunnel testing program to make it as aerodynamic as possible.

Though they're completely different in style, Kappa and P4/5 are similar in that there won't be any other vehicles like them, either now or in the future. And that's exactly what their owners demand.