626bhp, £145k, 18mpg: Real life with the mad Defender Octa

But there was always a curiosity, even with the restrained Faroe Green paint all Edition One cars wear. Edition Ones also have plenty of chopped carbonfibre trim inside and out (I'd happily do without it) but the mechanicals are as per the regular car, which starts at £148k. That means 400mm Brembo brakes up front, air suspension and a beefed-up driveline with two locking diffs.

With forged 20in wheels that are part military ops, part Group A WRC car, plus the honeycomb grilles, there's something aftermarket about the Octa. This undoubtedly gives it serious cachet for some onlookers (mostly young men). At the same time, it's too neat and homogeneous - too stylistically well done - to be anything other than factory, which appeals to the rest of us. In some ways it's the trail-bashing equivalent of a Ferrari 296 Speciale. It radiates a calibre that gives it more presence than any Cullinan or Urus.

Calibre, then. This is more than a body-kitted Defender P525 with a fruitier V8, as we know.

The throaty 5.0-litre unit in the P525 and the 4.4 in the Octa are unrelated, the former being supercharged and by JLR, and the latter hailing from Munich and being twin-turbocharged. Counterintuitively, it's the Octa's 626bhp engine that's a shade more subtle on a woofly cold start. It's a small but gratefully received edge when you live on a narrow street.

The difference in throttle response isn't huge, interestingly. The Octa's V8 may be blown but mild hybridisation gives a stab of torque-fill. Engine torque - a monumental 553lb ft - is then spread from 1800-5855rpm, which is to say it is omnipresent. For reasons we'll get to, in an Octa you can easily forget you're sitting four feet above the road in a near-three-tonne off-roader. Given this context, its A-to-B speed is head-scrambling.

No compromises or roll bars

Despite not being much of a super-SUV fan, I've loved blatting about in this thing. The suspension uses a cross-linked hydraulic set-up of the kind pioneered by McLaren. It negates the need for anti-roll bars, which tend to hurt ride quality on the straight-ahead. I can tell you after several thousand miles that it is almost worth buying an Octa for this alone.

Never mind the BMW M5 motor, an Octa - especially one wearing the 20in wheels and 60-section all-terrain tyres - rides nearly as well as the German super-saloon and better than any other Defender. Elsewhere, the suspension is redesigned from the geometry to the knuckles to the longer wishbones, but it is the natural-feeling roll, pitch and squat compensation of the cross-linked damping that makes the car an everyday marvel with gorgeous fluidity. In Octa mode, the car also knows when you're airborne and preloads the dampers for landing.

This is akin to the DRS wing on the latest Porsche 911 GT3 RS - the car people seem to love labelling as the Octa's supercar counterpoint. Utterly pointless 99.9% of the time but quietly quite cool. For me, the GT3 RS comparison isn't actually a good one. On the road the RS is often more disjointed and demanding than a humdrum Carrera, despite being stupendous in its preferred race track environment. Meanwhile, the Octa is a car you pull away in and know instantly that it is more polished and 'together' than the normal Defender in every respect, quite apart from its crushing ability on dirt trails.

It's counterintuitive but an Octa is surely the easiest Defender to drive day to day. The accuracy of the steering - the speed of which is increased from 17:1 to 13.7:1 and beautifully weighted - also makes it so simple to place.

Only parking holds you back. I'm a confident docker of vast barges but the track width and huge spare on the boot make sliding an Octa into a tight parallel-parking space something of an art. At least you needn't worry about the £5500 wheels, which you'd need a cliff face to kerb.

Going for broke

In January, when France and the UK got very snowy indeed, I took the Octa to remotest Castile and León. I knew the fuel economy was going to hurt like hell. Pounding fast along slushy European motorways then through the dramatic topography that takes you west from the Basque Country to the wild Picos de Europa mountains around Riaño all but guaranteed it.

On the way out, we took our time and managed around 22mpg, which I thought fair. On the way back? It was all a bit more rushed and culminated in a non-stop run from St-Jean-de-Luz to Calais. Result: 16.2mpg and 90 litres of unleaded guzzled in 320 miles or so. Oof. Even to a road tester that felt profligate, and I know even something as silly as a BMW X5 M would have returned closer to 25mpg. A form of air-to-air refuelling would have been genuinely handy.

Road roar was another thing to consider with the all-terrain Goodyears. Back in Blighty, I met up with a Defender-owning friend for lunch so he could have a go and then tell me about the Octa from the perspective of someone who daily drives a D300. Apart from being blown away by the performance - "brushing the throttle in fourth is like being flat out in second in my snotter" - and the handling, he noted the tyre noise straight away. In truth, it hadn't bothered me until that point, but once you do notice it you can't stop. (He also said the Defender's synthetic Ultrafabrics trim was proving "porous"; concerning for a man with two small children.)

Those caveats aside, I cannot think of many better tools for the job of bisecting Europe in the midwinter. For one thing, the Octa-specific 'Performance' seats are superb. I notice they're trading on eBay for £12k a pop. They're set high and the vantage point from an Octa is safariesque, but you never feel unduly perched and are able to enjoy rather a sporting driving position. It also lets you confidently put the Octa down a decent country road at speed, in a way that's almost a match for the Bentley Bentayga.

The Octa's ease at speed was a surprise. And to that speed, comfort and refreshing visibility, you can add security underwheel, practicality and a gold-plated sense of well-being in sub-zero temps, 1000 miles from home. Charming as the old-style Defender was, it could never do all that.

The bottom line

In the end we totalled 2600 miles. Efficiency? A wallet-hammering 18.4mpg. Maladies? None. Frustrations? Only that the absurdly heavy boot swings shut if you're on a slight angle. Even the ADAS are simple enough to prod into submission.

The fact is that, for activities approximating 'proper' use, an Octa happens to be one of the best cars in the world. Rarely, if ever, have Isofix points, supercar damping, toughness, genuinely good handling and fine long-distance manners mingled in harmony as they do here. Is it worth putting up with the odd bout of self-consciousness? It's not even a serious question.

The world's most capable car?

Things I think when driving the Defender Octa: how is it that a car this good off-road can be so pleasurable on it? Will I fit through that gap? Do I look like a bit of a berk? Gosh, how did they make it this good? I go back and forth a bit on what I think is the most broadly capable car in the world. Sometimes I think it could be a Bentley Bentayga because it has to do some off-road things, plus tow 3500kg, be a true luxury car and do anything up to 190mph.

Then I think that maybe it's a Range Rover Sport SVR, because it retains most of the luxury stuff, is even more dynamically adept on circuit, adds even more off-road ability and oversteers quite a lot. A Porsche Cayenne can pull some dynamic moves too (at the expense, I think it's fair to say, of overall plushness). And then the Octa arrives, which pushes the soft-riding but with exceptional body control levels further than anything I can think of, with a toughness and resistance to rocks and an ability to jump that makes it feel like some kind of rally raid car. It has all that a Ford Ranger Raptor can do in those circumstances, but with superior isolation.