The FXX K measures 194mm longer and 59mm wider than the LaFerrari, at 4896mm and 2051mm respectively, but shares the same height of 1116mm as well as its 2650mm wheelbase. Ferrari has also dropped some 90kg from LaFerrari's kerb weight, meaning the new FXX K weighs in at around 1255kg.
Stylistically, the FXX K looks like a race-inspired evolution of LaFerrari's shape. A new twin-profile spoiler and large splitter – which is 30mm lower than on LaFerrari and includes a central gap to channel air flow– can be seen at the front. This works in conjunction with the larger side sills running down the flanks of the car to stop air gathering underneath.
At the rear, a large, twin-pronged permanent spoiler features alongside a secondary mobile spoiler which can extend on the move. The distinctive shape of the rear is designed to boost downforce, and is helped by the new rear diffuser.
Ferrari says this has helped improve downforce by 50 per cent compared to LaFerrari, resulting in the FXX K producing 540kg of downforce at 124mph. The FXX K can lap Ferrari's Fiorano test track in just 1m 14sec, some five seconds faster than LaFerrari.
Inside, the FXX K does away with many of the luxuries of LaFerrari, although it keeps a digitised instrument cluster.
The FXX K sits on special slick Pirelli P-Zero tyres, which incorporate sensors to measure acceleration, temperature and pressure. Carbon-ceramic brakes, manufactured by Brembo, also feature. The car's traction control, Side Slip Angle Control and electronic differential have been specially calibrated to suit the performance rubber, while drivers can control ABS settings via the steering wheel.
Whereas the standard LaFerrari featured a double wishbone suspension set-up front and rear, the FXX K instead adopts a multi-link rear set-up.
Key changes made to the LaFerrari's V12 engine include new camshafts, a modified valve train, redesigned intake manifolds, and the use of mechanical rather than hydraulic tappets. The car's exhaust system has also been modified.
Similarly, the HY-KERS system has been upgraded, giving drivers the option of controlling power with four different modes with the 'Manettino' controller.
Qualify mode provides maximum power for a short number of laps, while Long Run optimises performance for longer stints. Manual Boost mode delivers instant maximum torque, while Fast Charge mode can be used to recharge the car's battery.
The Maranello-based firm says as the FXX K isn't homologated, it will "never" be used in competition. In a statement, Ferrari said the car was developed "to be completely uncompromising, incorporating technological innovations that will guarantee an unprecedented driving experience".
The FXX K’s main rival is McLaren’s P1 GTR, which made its debut at the Pebble Beach concours earlier this year. It will go on sale next summer and is powered by a 986bhp 3.8-litre twin-turbocharged V8 engine working as part of a hybrid powertrain. The P1 GTR will only be offered to existing P1 owners at a cost of £1.98 million.
As an ongoing development project, technology and knowledge harvested from development of the FXX K will inform future Ferrari road cars including the next 458 and F12 Berlinetta.
Speaking at the launch of the new model in Abu Dhabi, Ferrari head of marketing Nicola Boari said the FXX K was "not a track version of LaFerrari. We use its structure and powertrain," he said, but stressed that everything else about the FXX K was learnt on the track.
On the question of whether tech from the FXX K could ever be used to enhance the road-going LaFerrari, Boari said that while engineering new technology to turn LaFerrari into a racer was doable, "doing the reverse is impossible."
An even more hardcore 'Evoluzione' version of the FXX K has been deemed possible by Ferrari test driver Marc Gené, but is unlikely to appear for a number of years. "Right now, I think we cannot improve that car,” he told Autocar. “But no doubt something will come up. I wouldn’t be surprised if it happens, but it won’t be in two years. Cars like this have a life cycle of around ten years."
However, it’s unlikely that any FXX K Evoluzione model would come with any more power than the standard car. “The XXK has 1021bhp," said Gené. "I cannot see cars of the future having more power than that. Now the focus will be on efficiency and then on power-to-weight ratio. Weight is critical.
“The future will be in weight reduction, in efficiency and also in handling. You can improve the handling with electronics, aerodynamics and set-up.”
“It will be like the 458 Speciale, which comes towards the end of the lifecycle. Then technology from that evolution will appear on the next model.”
Previous entries in Ferrari's exclusive owner-driver programme include the Enzo-based FXX, which is powered by an 848bhp 6.2-litre V12 engine, and the 720bhp 599XX.
Read Autocar's full LaFerrari review
The cars of Ferrari's XX programme
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