McLaren upgrades its GT3 race car to let loose an unhinged track-day weapon

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So what exactly is the McLaren 720S GT3X? One of the fastest track-day weapons ever made? A race car that can’t be raced? A rich person’s plaything? The truth is that it’s all of these things. And it’s also one of the most sensational four-wheeled experiences that (quite a lot) of money can buy.

You’ve probably already seen and read quite a bit about this mighty McLaren, but it’s probably worth a quick recap. Essentially, it’s a GT3 racer uncorked; one that dispenses with the closely fought slicks-and-wings-sports-car category’s ‘balance of performance’ power cap of around 500bhp and turns up the wick to 710bhp – or 740bhp if you’re brave enough for the brief squirts of push-to-pass power injection.

To achieve this, the GT3 engine is ditched and replaced by McLaren’s familiar M840T twin-turbocharged 4.0-litre V8, but a version that’s handbuilt with stronger pistons, revised heads, a titanium exhaust and electronic mapping that’s massaged to favour top-end frenzy at the expense of low-rev muscle.

It’s mated to a six-speed Xtrac paddle-shift gearbox that drives the rear wheels through a 12-stage electronic traction-control system. The rest of the car is almost pure GT3, with the same carbonfibre tub and exterior panels, impressive-looking aerodynamic package and suspension set-up. To all intents and purposes, it’s a bona fide race car, albeit one that, due to its outrageous power boost, is ineligible to race.

Only inside are there changes, necessary to accommodate the revised roll cage that’s required for the addition of a passenger seat, which for most wealthy owners will be occupied by an instructor. Today, however, it’s full of factory ace Euan Hankey, who has already taken us for some wild-eyed laps around the spectacularly serpentine Navarra circuit in Spain as he gets heat into the Pirelli tyres and carbon-ceramic brakes. Now, however, it’s our turn.

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You’re strapped in tight to the carbonfibre racing seat, while the adjustable pedal box and steering column allow you to settle yourself just so in the recumbent driving position. Ahead of you is a yoke-style steering ‘wheel’ peppered with buttons that control everything from the traction control through to the ABS calibration and that push-to-pass function.

Once you’re settled, McLaren’s technicians drop the car off its air jacks and it lands with a thump, then the engine fires with an angry, gravelly bark. You need to use the clutch (and plenty of revs) to move off, but once under way, this is a two-pedal car. Then it’s down the pitlane and out onto the circuit for what turns out to be some of the most mind-bending, exhilarating and exhausting laps you’re ever likely to experience.

We’ve already explored the circuit in McLaren 765LT road cars but, racing lines aside, all that gained knowledge is pretty much redundant. Whereas a lift or a squeeze of the brakes was required before through the quick stuff, now you’re simply turning and going, relying on a combination of bravery (in short supply), the incredible aero and mechanical grip, plus Hankey’s surprising encouragement to keep the throttle pinned when every cell in your body is screaming at you to lift. The mid-corner adhesion is tenacious enough to squeeze you hip-crushingly hard against the seat bolsters.

It’s the same everywhere around the circuit. You find that you can never brake hard and late enough, and soon your left leg is aching from the effort of stamping on the pedal with a force that you expect to trigger the ABS but which never does. Then there’s the grip from the gumball Pirellis (a special supersoft compound not allowed in GT3 racing), which is eye-bulgingly astounding, the quick and precise steering revealing turn-in bite is as tight as a Doberman’s grip on a juicy bone. With practice, you can use it to trail the brakes and rotate the car neatly into slower corners.

Traction is incredible too, with the electronics (we’ve dialled in a pretty much halfway-house stage seven) allowing just a subtle flare of wheelspin as you get hard on the throttle as the car straightens at the corner exit.

As you would expect, the combination of more than 700bhp, a 1210kg kerb weight and closely stacked gears makes the GT3X very quick down the straights, but such is the brilliance of the rest of the car that it’s the least mind-blowing dynamic aspect (the Ferrari SF90 Stradale is likely a little faster once rolling).

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Still, the V8 never sounds anything less than angry, and it’s best at the top end, when the revs pile on with a frenzy that has you banging up the gearbox as quick as your fingers can pull on the paddles. And there’s a palpable kick in the back when you hit that push-to-pass button.

After a few laps, you’ve only scratched the surface of this car’s ability, yet your race suit is drenched in sweat and your limbs are aching from the forces involved. Equally frazzled is your brain. The concentration required to stay neat and tidy at a half-decent pace gives you renewed respect for racers.

Crucially, though, your grins are huge and adrenaline is coursing through your veins. It has been an intoxicating experience that you want to do again and again so as to learn this remarkable car’s abilities.

James Disdale

James Disdale
Title: Special correspondent

James is a special correspondent for Autocar, which means he turns his hand to pretty much anything, including delivering first drive verdicts, gathering together group tests, formulating features and keeping Autocar.co.uk topped-up with the latest news and reviews. He also co-hosts the odd podcast and occasional video with Autocar’s esteemed Editor-at-large, Matt Prior.

For more than a decade and a half James has been writing about cars, in which time he has driven pretty much everything from humble hatchbacks to the highest of high performance machines. Having started his automotive career on, ahem, another weekly automotive magazine, he rose through the ranks and spent many years running that title’s road test desk. This was followed by a stint doing the same job for monthly title, evo, before starting a freelance career in 2019. The less said about his wilderness, post-university years selling mobile phones and insurance, the better.