Woking, Surrey - This is only the fourth McLaren model in more than two decades to carry the Longtail nameplate, reserved for the most performance-focused street-legal weapons in the Woking arsenal.

OK, it’s based on the 570S Coupé, but it’s 74mm longer overall thanks an extended front splitter, lengthened rear diffuser and fixed rear wing. Almost one in four of the components on this car are different than those on the 570S and most, though not all, of the changes are about saving weight. With all the lightest options fitted, it’s 96 kilograms lighter than a standard 570S at just 1247kg dry - that’s a huge difference at this level of performance, where weight savings are commonly measured in grams.

It has new, more aerodynamic carbon-fibre body panels, and a special free-flow exhaust system, even shorter and more extreme than that of the McLaren Senna, that exits over the top of the rear subframe rather than under it and speaks to the world with distinctive authority.

Its voice is that of a twin-turbocharged, 3.8-litre V8 with an uprated cooling system and reduced back pressure that is quoted at 441kW and 620Nm; with every lightweight option fitted that gives it a power-to-weight ratio of 354kW per ton - about the same as a 600cc supersports motorcycle.

The interior is trimmed - if you can call it that - in carbon fibre and lightweight alcantara synthetic suede, including carbon-fibre racing seats borrowed from the iconic McLaren P1 - or you can opt for the even lighter seats from the Senna. Further weight-shedding options include a carbon-fibre roof and vented carbon-fibre front wings.

But this car is not only about the numbers - it’s also about the feel, about precise feedback and instant response, so it has the forged aluminium double-wishbone suspension and lightweight brakes from the second-generation Super Series, special track-focused Pirelli P Zero Trofeo R tyres; quicker steering; sharpened responses from the throttle and brake pedals and significantly firmer engine mounts.

Without having seen one, let alone driven it, we would say this is not going to be a comfortable car. It will vibrate, it will jar you, the cabin will get noticeably warm when it’s driven the way it‘s meant to be driven, and you will probably be able to smell the hot engine oil after a dozen laps of your favourite racetrack. It will engage all your senses, unfiltered and at full volume - and it will probably be the most fun you can have with your clothes on.

McLaren hasn’t put a physical limit on the number of 600 LTs to be built - but because of the special carbon-fibre body panels it wears, it won’t be many. Production will start in October 2018 and go on for about 12 months, with build slots scheduled around existing Sports and Super Series models, as well as the rest of the already sold-out Senna, Senna GTR and BP23 production. A handful of those build slots have been allocated to South Africa, with indicative pricing starting around R5.5 million.

IOL Motoring