Ferrari’s Corse Clienti XX Programme—which began 20 years ago with a track-only performance variant developed from the Enzo—while simultaneously researching future vehicle development and rewarding loyal clients, was undeniably a smashing success that begged a second entry. Sure enough, four years after the FXX’s introduction, Ferrari unveiled a front-engine companion to the model, appropriately dubbed the 599XX. The base 599 GTB Fiorano was already powered by a derivation of the Enzo’s 6.0-litre V-12, so it was the perfect host for a new Corse Clienti excursion.

Though the 599XX resembles the 599 GTB in general form, most of the bodywork and engine ancillaries were replaced or upgraded. Functional vents and scoops decorate nearly every panel of the car, instantly clarifying the degree of aerodynamic development undertaken. So extreme was the engineering of airflow and downforce on the 599XX that two fans were installed in the boot to draw air from the undertray and funnel it through the former tail lamp valances.

The revised Tipo F140C engine aggressively capitalised on the body’s aerodynamic development, with the modified motor generating 730 horsepower and 506 pound-feet of torque, enough to catapult the car from 0-100 km/h in just 2.9 seconds. In addition to upgrades such as mechanical tappets and graphite-coated pistons, Ferrari implemented a particularly unusual feature for a race-prepared motor, guaranteeing the engine for at least 5,000 kilometres (almost daring customers to find the limits during track events).

Suspension engineering was particularly astonishing, with state-of-the-art SCM Magnetorheological damping contributing to traction control, which was adjustable via a dash-mounted “Manettino”, offering nine different graduated settings. The 599XX’s interior is no less competition-oriented, with a roll cage and a single carbon-fibre dash panel dictating the spartan cockpit, and with nearly all other amenities stripped away. The surprising presence of air conditioning clarifies that the 599XX was a track car that was intended to be enjoyed by customers as much as it was strenuously driven.

The 599XX soon proved its mettle when it matched the FXX’s lap times at the Fiorano test track. Ferrari then sent an example to the Nürburgring where, on 21 April 2010, Raffaele de Simone achieved an astonishing time of 6min58.16sec, breaking the lap record and proving to be even faster than the Enzo (7m25.7s). Rarely has a production-based track car been built that so comprehensively utilises every available technology to optimise performance.

In 2011, Ferrari further enhanced the 599XX with the offering of a new Evoluzione package that took the already-potent model to the upper stratosphere of performance. No mere cosmetic evolution, this was a thorough metamorphosis, with power rising to 740 horsepower, torque to 516 pound-feet, and a shortened final drive ratio noticeably sharpening acceleration. But power was only part of the story. The Evo introduced one of the earliest applications of active aerodynamics in a Ferrari vehicle, including a Formula 1-inspired DRS (Drag Reduction System) integrated into a twin-profile rear wing. Governed by onboard sensors, this system adapted to throttle input, steering angle, and yaw to continuously optimise downforce and reduce drag at speed.

Other Evo upgrades included a lightweight exhaust system with side-pipes, revised suspension geometry, and bespoke, track-specific wheels shod with Pirelli racing slicks. The result was astonishing: a Fiorano lap time of just 1m15s, placing the Evo comfortably ahead of even the Ferrari Enzo and many purpose-built GT race cars.

Manufactured in a sparing quantity of approximately just 45 examples, the 599XX was intended to be driven at track events only, and it was never homologated for legal road use. Customers were encouraged to enter their cars in the XX Programme’s specialised calendar of non-competitive events held around the world and run by Ferrari Corse Clienti. They would compete only against the clock in an attempt to improve their lap times. These special quasi-development cars are a fascinating extension of the XX Programme in front-engine-form, and they appropriately strike a brilliant counterpoint to the FXX.

Chassis number 187956 is among the final batch of cars built in 2012. It was allocated to a client based in the United States and finished in Rosso Fuoco paint. As a result of its late production, chassis 187956 is one of the few examples of the 599XX that was built from new with the desirable Evo upgrade. Decorated with #19, the 599XX benefits from long-time care by the Ferrari factory’s XX division. After being acquired by the consignor, the car was wrapped in a Blu Corsa Opaco livery, effectively matching similarly styled stablemates, the FXX and FXX K.

The 599XX was enjoyed in Corse Clienti events, including the 2021, 2022, and 2023 Finali Mondiali events at Mugello. The odometer currently reads 10,806 kilometres, reflecting a life of spirited-but-limited use. The technical reports tells us that the engine has very little wear (2 per cent). Having not been driven for two years, it is recommend that the car should be serviced prior to participation in its next event.

Marque enthusiasts with particular interest in the factory’s sportscar development programmes will not want to miss this rare opportunity to acquire a bona fide track-only Ferrari test machine, one with a presence both menacing and beautiful. Given the current timing of the XX Programme’s 20th anniversary, there could hardly be a more appropriate moment to acquire this scintillating 599XX Evo. It invites the next caretaker to indulge in astonishingly fast hot laps, or exhibition opportunities at Ferrari focused events. In any case, this rare and technologically flawless 599XX would crown most modern performance-oriented collections.