In addition to production vehicles, Pininfarina creates prototype, show, and custom cars for auto manufacturers, as well as private clients. Most prototypes -such as the Ferrari Mythos- have served solely as concept cars, although several have become production models, including the Ferrari 612 and Ferrari F50.

A recent privately-commissioned custom example was the Ferrari P4/5 of 2006, a one-car rebody (changing the exterior design) of the Enzo Ferrari according to the client's specifications.

Its design began in September 2005 with sketches by Jason Castriota moving through computer aided sculpture and stringent wind tunnel testing. More than 200 components were designed especially for the car though the engine, drivetrain and many other components are simply modified from the original Enzo Ferrari. The Vehicle Identification Number (VIN) is unchanged from the Enzo it was derived from. The P4/5 was publicly revealed on August 18, 2006 at the Pebble Beach Concours d'Elégance and shown again at the Paris Motor Show in late September.