Phowar! Look at the airbrakes on that! Don't get many of them to the pound, missus.

Erm, actually you do get quite a few of those to the pound, because they're made of carbon fibre.

Ah. Oh. Sorry. Was I being crude?

Just a tad, yes but it's slightly tricky to get away from the whole enhanced-buttocks thing when talking about this, the McLaren 657LT. The LT stands for Long Tail, and the car has been produced both to further optimise the aerodynamic package of the 650S supercar for track use. It is also a bit of a 20th anniversary tilt of the hat to the amazing McLaren F1 GTRs that raced at Le Mans and in the BPR Endurance series (although the original long-tail F1 GTR didn't come along until 1997, as a response to the Mercedes-Benz CLK GTR and the Porsche 911 GT1).

So, obviously, the 675LT is a tad longer than the standard 650S, but it's also lighter - McLaren has shaved a scarcely believable 100kg from the already-featherweight 650S. That means it tips the scales at just 1,230kg - or about as much as a lightly-specified Ford Focus.

Butt (sorry) it has monster power. The 675 refers to its horsepower output, while torque jumps to a massive 700Nm. All of that comes from a highly modified version of the 3.8-litre twin-turbo V8 engine we've already seen in the MP4-12, the 650S and the P1. Upgrades include new, more efficient turbos, detail design changes to the cylinder heads and exhaust manifolds, new camshaft and lightweight connecting rods, plus a faster-flowing fuel pump and delivery system. Performance is simply off the scale - 0-100km/h in 2.9 seconds, 0-200km/h in 7 seconds, or about the time a decent hot hatch takes to get to 100km/h. And a top speed of 330km/h, just breaking the 205mph barrier.

Helping to control and focus all of that power is a thorough aerodynamic shakeup. The longer tail is the most obvious bit, but the air-brake that helps slow and steady the car is also 50 per cent bigger than on the standard car (yet actually lighter thanks to clever construction). Up front, that's balanced by a more aggressive front splitter, which McLaren says "works the air harder."

Two circular exhaust pipes, forged from titanium, exit centrally through exposed bodywork below the rear wing. Despite a more complex design, the bespoke crossover system is designed to optimise performance and reduce weight, saving 1.1kg. The rear deck and sections flanking the exhaust pipes remain exposed; designed to evacuate hot air from the engine bay as efficiently as possible, while a lightweight polycarbonate rear screen features further louvres. A louvred carbon-fibre rear bumper reduces air pressure too. This is all proper race car aero stuff, yet although the 675LT is focused on track performance; it is fully road-legal too.

McLaren will offer the LT in five 'By McLaren' hero specifications, which includes four bespoke colours never previously offered: Silica White, Delta Red, Napier Green and Chicane Grey. The famous heritage McLaren Orange will also be available and the stripped out interior comes with carefully selected materials and colours.

The 675LT will get its full public debut at the Geneva Motor Show next week.