This is the new McLaren 675 LT, revealed here ahead of its world premiere at next week's Geneva Motor Show. And the big news? It's quick.

Before we get to that, some context. Think of the 675 LT - that's LT for 'Longtail' - a lighter, harder and more powerful version of the 650S. It's 'fully track-focused", but is road legal, and in this LT guise will be offered as a Coupe only.

McLaren tells us that a third of this 675 LT's parts have been changed compared to the 650S, while that 3.8-litre twin-turbo V8 has had more than half of its parts changed to deliver more power, torque and 'driveability'. Things like better turbos, changes to the cylinder head and exhaust manifolds, new cams, lighter connecting rods and a faster fuel pump.

Just how much more power does it produce over the 650S? A devilishly sounding 666bhp (675PS, hence the name) at 7,100rpm, and 516lb ft of torque. It's still channeled through a seven-speed dual clutch gearbox and sent to the rear wheels.

Changes extend beyond the engine, too; it's lighter, with all sorts of aero trickery at work. McLaren tells us weight reduction has been the focus of this new Longtail, and thanks to carbon fibre for the body panels, that lightweight engine, and lightened chassis and body structure parts, the whole thing is 100kg lighter than the 650S. We're talking a dry weight of 1230kg, meaning power to weight stands at 541bhp per tonne.

There's a new front bumper, a carbon fibre front splitter, new front wing end plates (for additional downforce), new CF side sills, an air intake at the rear arch and a reprofiled airbake, itself 50 per cent larger than on other Super Series cars. There's even CF rear wings, too.

A new forged titanium exhaust system saves 1.1kg alone, while McLaren has also deemed it prudent to fit a polycarbonate rear screen and CF rear diffuser.

So what does this all mean? You're looking at a 0-62mph time of 2.9 seconds, a 0-124mph time of 7.9 seconds, and a top speed of 205mph; quicker to 62mph than the 650S, but slower by 2mph on top speed. On track however, we suspect the differences over the 650S will be larger...

"This is a car that is as exciting to look at as it is to drive," says McLaren. "It also embodies the key attributes of the 'Longtail' ethos targeting light weight, optimised aerodynamics, increased power, track-focused dynamics and driver engagement."

We'll see it for real at Geneva next week. Expect a price bump over the 650S Coupe's £195k starting price.