Weight has been cut elsewhere through the use of thinner glass, carbonfibre for more of the body panels, top exit exhausts that have less pipework and lightened suspension components.
The 600LT’s rear end stretches 47mm further back than the rear of a 570S, which is how McLaren justifies the Longtail nomenclature. You will need to be very familiar with McLaren’s model range to recognise that in person, but the one-piece carbonfibre rear diffuser and bumper assembly is not at all difficult to spot.
Whereas a 570S is lift neutral at 155mph, the 600LT actually produces 100kg of downforce, thanks to an aggressive front splitter and new side skirts, that prominent diffuser and a fairly modest rear wing.
The freer breathing exhaust system and new engine management software lift power by 30bhp over the 570S to 592bhp. The engine internals, though, are untouched. McLaren quotes a 2.9sec 0-62mph time a top speed of 204mph.
Running 8mm closer to the road, the 600LT sits on springs that are 13% stiffer at the front and 34% at the rear, and retuned dampers. The anti-roll bars are stiffer, too, by 50% at the front and 25% at the rear.
The brakes are lifted from the 720S while the standard-fit tyre is a Pirelli P Zero Trofeo R - understandably, McLaren chooses not to disclose exactly how much of the 600LT’s newfound cornering ability is down to its rubber, but you can be sure it is a substantial amount - although our test car on this occasion was fitted with far less aggressive P Zeros.
How does the 600LT perform on the limit?
A lot like the 570S. That is, the 600LT is explosively fast, it steers beautifully and it is shot through with agility and handling precision.
When the uprated model is shorn of its ultra-sticky track-day tyres, the differences between the two cars are not enormous. What you do notice, however, is a much richer and more tuneful soundtrack - thanks to those top exit exhausts - and an even more panic-inducing way of climbing from a moderate speed to a potentially custodial one in the lower gears in what feels like no time at all.
Steer the 600LT through a sequence of slow- and medium-speed bends and you won’t be able to tell it apart from the 570S - again, the Trofeo R tyres will undoubtedly make it feel very different to that model - but when you point it along a gently meandering road, perhaps one that has a large drop to one side and a sheer rock face to the other, you do appreciate the 600LT’s even sharper handling responses and its yet more pinpoint steering. It is so intuitive and communicative that you think rather than drive it along that sort of road.
With its uncompromising chassis settings, the 600LT does inevitably feel less forgiving on a bumpy road, but in what little suspension travel it does have there is exceptionally well-judged damping. That means the car can feel busy over bumps and ridges, but never brittle or uncomfortable. On smoother roads, you’ll never give the car’s ride quality a second thought.
With close to 600bhp but the same internals as the 570S’s motor, the 600LT’s engine feels as though it is close to being overstretched. Its top end is frantic, but the bottom end is almost entirely lifeless. Only once it reaches 3500rpm does it start to do anything, and it needs another 1000rpm on top of that before it feels particularly strong.
The brake pedal can be frustrating, too, because in what you could describe as typical McLaren fashion, there is an inch or so of travel right at the top of the pedal that seems to do nothing at all. When you hit the brake pedal looking for a shot of confidence, perhaps as you sprint wide-eyed down an Alpine pass, the 600LT does not immediately give it to you.