What's all this about?

This is all about the Land Rover Defender going to new heights. It's called the Octa and it's a 635hp, 750Nm example of the big 4x4, with advanced semi-active suspension, butch looks and a subtly enhanced interior. Oh, and a price tag starting from £145,300.

No, it employs the same 4.4-litre biturbo V8 with mild-hybrid tech as the Range Rover Sport SV. Employed only in the 110 body, the Octa's powertrain is enough to shunt the vehicle from 0-62mph in just 4.0 seconds with a time-restricted launch control phase giving it 800Nm for a brief period, and on to a top speed of 155mph.

That, though, is if you opt to equip the 22-inch alloys with road-biased tyres. The Octa also comes with 20-inch wheels fitted with 33-inch off-road rubber, of two levels. Opt for the first of these and the Landie is then limited to 130mph, with the most serious tyres restricting the Octa to just 100mph.

Never mind; top speeds are irrelevant, mainly, it's how you get there that matters. And Land Rover says it has developed the Octa with a specific development programme that has tried to ensure it is just as quick in the rough stuff as it is on tarmac.

Oh, really? What hardware does it have?

The Octa deploys the 6D Dynamics suspension as seen on the RR Sport SV, which means it uses hydraulically linked dampers which can negate pitch and roll. This makes the Defender more assured on tarmac, but crucially it also gives it greater wheel articulation for off-roading, so Land Rover is feeling bold enough to claim that this car is better away from the metalled surfaces than its source material is; some assertion, that. It still has the company's fabled Terrain Response system, with various settings, for mud, snow, rocks, gravel and so on, and an eight-speed automatic transmission blessed with both high- and low-ratio gears. Oh, and it can wade through a metre of water.

A metre?!

Yup. Part of the Octa's impressive appearance is that it is 68mm wider than the standard car, thanks to enlarged arches and a wider track for the axles beneath, but it's also 28mm taller too. And that increases the wading depth to 1,000mm, which makes this one of the most capable factory 4x4s yet seen when it comes to fording through rivers and the like.

In terms of the appearance, aside from the blistered wheel arches then there are also bespoke bumpers front and rear for the Defender Octa, plenty of black on the tailgate, and the encircled-diamond logo that will be the Octa signature going forward. In case you're wondering, it's called that because the structure of diamond is octagonal, so giving this ultra-Defender that particular model name, instead of SV, connotes that this is a 'rare combination of extreme toughness and luxury'.

Oh, look at the quad exhausts, too. They're of a new, specific design for the Octa, and they have angled tips so that the departure angle of the Land Rover is preserved for serious off-roading duties.

How about the cabin?

Broadly as per the regular 110, only with some Octa-specific materials and trim finishes, including chopped carbon-fibre, something you can have on the exterior in certain places. There's also an Octa button on the steering wheel, which if you click it puts the car into its most dynamic on-road setting, and if you press and hold it then you get the Land Rover all geared up to go tearing through the rough stuff. Beyond that, there are even 'Body and Soul Seats' that are linked to the sound system and which can pulse in time to the music, so you feel your favourite song as much as hear it.

Anyway, order books for the Land Rover Defender Octa will open soon, while it will make its dynamic debut at the Goodwood Festival of Speed in early July. The price of £145,300 is for the regular Octa, by the way, with a fully loaded Edition One - complete with carbon flourishes on the exterior and more kit - available for a limited time from £160,800.