New McLaren 620R is road-legal GT4 racer

McLaren has unwrapped an extreme ultra-limited road-legal version of its 570S GT4 and called it the 620R.

On sale early in 2020 priced at £250,000 ($A480,000), just 350 of the flagship Sport Series will be made and all of them are expected to be snapped up fast by wealthy track-day enthusiasts given the car-maker's claim that the latest McLaren 620R is nothing short of "road-legal version of a race car".

Better still, free of any motorsport restrictions, engineers could uncork the racer's twin-turbocharged 3.8-litre V8 to produce 620hp (456kW) – a big lift from the GT4's 313kW and 15kW more than the 600LT.

Now the most powerful member of the Sport Series line-up, thanks to a mighty 620Nm torque peak, McLaren claims the 620R can scorch from rest to 100km/h in just two seconds, complete the 0-200km/h dash in only 8.1 seconds and top out at 322km/h.

Like the regular 570S, the seven-speed dual-clutch auto carries over and the 620R remains rear-wheel drive but stiffer engine and transmission mounts were needed to cope with the performance on tap.

On track, the 620R borrows much from the GT4 racer, getting an adjustable carbon-fibre rear wing, although to keep it on the right side of the law a small third brake light has been incorporated.

That big rear wing is said to be capable of being adjusted in one of three settings to help the 620R generate up to 185kg of downforce.

Meanwhile, at the front of the car a reprofiled front bumper that appears to have grown a large front splitter and dive planes are said to be more adept at managing airflow.

Helping it corner like a full-fat race car, the 600LT's road car suspension has been dumped for a set of adjustable coilover springs and damper units that have a mind-boggling 32 individual settings.

Stiffer anti-roll bars and more track-focused carbon-ceramic brakes have also been introduced, while stickier Pirelli P Zero Trofeo R cut-slick tyres are standard, with the option of full slicks for track use.

Cutting the kilos inside, the air-con and main infotainment system has been ditched, although both can be put back by request – something that can't be said for the glovebox and floor mats, both of which have been banished.

The result, McLaren claims, is a weight-saving of around 30kg over the standard 570S.

If you re-order the infotainment system, the touch-screen that returns is said to feature a track telemetry system and three (optional) cameras to help you nail the perfect lap.

Six-point lightweight carbon-fibre race seats, door pull straps and a carbon-fibre steering wheel, shift paddles and centre console complete the changes.

If you order one of the numbered 350 620Rs there's the choice of just three exterior paint colours: orange with white racing stripes or white or black with orange stripes.

Want something different or fancy a decal inspired by the Senna GTR? McLaren's bespoke MSO division can, and will, happily oblige.

Stump up the full $480,000 (before taxes) for the 620R and McLaren says that if you order your car in Europe or North America it will throw in a full day's race tuition.

Deliveries are said to begin as soon as this February 2020, although Australian sales have yet to be confirmed.