The new XJR575 model is powered by a version of the company's 5.0-litre supercharged V8 boasting 423kW of power and 700Nm of torque.
Drive goes to the rear wheels via an eight-speed automatic, and Jaguar Land Rover says the sedan is capable of blasting past the 0-100km/h standard in 4.4 seconds, and hitting a top speed of 300km/h.
Compared to the outgoing XJR, the new XJR575 has an 18kW advantage and is 0.2s quicker to 100km/h.
The XJR575 is distinguished from lesser models by its unique bonnet vents, rear spoiler, side sills, and front bumper design. There's also gloss black lower air intakes, and 20-inch alloy wheels.
On the inside, the XJR575 features 575 branding on the dashboard, tread plates, and the diamond-quilted leather seats.
Other XJ models
New features for updated XJ range include full LED headlights with the "double J-Blade" daytime running lights, and a larger 10.0-inch touchscreen with the latest Touch Pro infotainment system, which incorporates a 4G Wi-Fi hot spot.
The XJ's safety package has been upgraded with autonomous emergency braking that now includes pedestrian detection, as well as driver fatigue monitoring, lane keeping assistance, and forward traffic detection.
In Europe, the revised XJ range will be offered in Premium Luxury, Portfolio, R-Sport, Autobiography, and XJR575 trims. Engine choices include a 250kW 3.0-litre supercharged V6, and a 375kW supercharged 5.0-litre V8, as well as a 221kW 2.0-litre turbo-diesel V6 and XJR575's 423kW V8.
The latest update will keep the eight-year old XJ ticking along until a new model is ready. Rumours indicate the new range-topping sedan could be ready by 2019, and might be an electric-only proposition or a Panamera-fighter.
The updated XJ range goes on sale locally during the first quarter of 2018, including the new hero XJR575.
Pricing, specifications and model availability will be announced closer to the car's on-sale date.