Tough Mudder: Land Rover Defender Octa v Mercedes-AMG G63

It has the heart of a supercar, its 4-litre twin-turbo V8 producing 577bhp and 627lb ft with a little help from a mild hybrid system. Maybe the most baffling thing about this car is its price – more than £200,000 in MANUFAKTUR Edition specification, like this press car – or rather the fact that so many people are in such a hurry to pay it. The G63 range starts at £189,375. If ever there was a car to prove that people buy expensive machines like these entirely with the heart not the head, the G63 is it.

In many ways, the Defender Octa is even madder. It’s certainly more powerful, its BMW-derived 4.4-litre twin-turbo V8 (also mild hybrid) firing 626bhp in all four directions, though it lacks 74lb ft of torque compared to the AMG.

Like its rival the Defender uses sophisticated hydraulically connected dampers to control roll, pitch and squat, but with air springs it can alter its ride height to suit the terrain. It makes do with just centre and rear differential locks, but its BFGoodrich off-road tyres are far better suited to scrabbling away at dirt and rocks. The Octa’s wheels are two inches smaller (20in compared to 22) which means a massive amount of additional sidewall, a fact that would be on my mind for much of the day.

If there are price conscious buyers in this space, the Defender is the clear choice – it starts at £148,045, undercutting the G63 by an entire VW Golf GTI with a few extras.

A quick word on interiors before we fire up the V8s. The Land Rover’s feels roomier, tougher and more hard-wearing, particularly with wipe-clean polyurethane fabric across the seats, dash and doors (you can pay extra for semi-aniline leather if luxury is more important than durability), while the Mercedes’ cabin is a curious blend of workmanlike architecture with shimmering screens, soft leather, high-grade metal switchgear and porous wood. It feels more upmarket. Yet the G63’s rear seat package is pretty poor with marginal legroom, while the optional TV screens are so large and close you’ll go cross-eyed if you look at them too long. The Defender is almost six inches longer nose to tail, which aids both rear seat and boot space.

Both are ludicrously, hilariously fast. It would take a runway and timing gear to establish which one was quicker. I won’t try to guess here. The Land Rover is 10 per cent lighter and a bit more powerful, but the Mercedes has more torque and better grip off the line, so each has its advantages. It scarcely matters though. They’re not just searingly quick, for each has an engine that’s responsive, energetic and eager to rev all the way out as well. The Octa’s soundtrack is more muted than the G63’s loud Nascar rumble, which is made more prominent still by those extravagant side exit exhausts just a few feet from your right ear.

Neither has the sharpest, snappiest gearbox in manual mode, and in any other kind of performance car I would take issue with their reluctance to shift down when you ask them to. In machines as big and heavy as these, it rarely seems like an issue.

We’re here but need to be a couple of miles away over there, in the picturesque gorge that photographer Mark Riccioni has been desperate to investigate. Connecting us to it is a wide, mostly straight sealed road that’s littered with gravel, rocks and deep potholes. It’s the sort of ground the Land Rover was built for, so I press the flap at the bottom of the steering wheel to toggle ‘Octa’ mode, point the nose at the gorge and let all those horses rip. What happens next is strange, like there’s a fault in the messages being sent to your brain by your eyes and backside. By sight you would swear the car should be rocking and bouncing and leaping about like a dinghy in a storm, yet by feel you’d say the road was perfectly paved like a freshly resurfaced race track.

It doesn’t compute. The Octa’s hydraulic suspension, air springs and pillowy sidewalls mean it glides along this crumbling track. You rattle it over the potholes and feel them, for sure, but you don’t worry about punching a strut through a tower or bursting a tyre. This is its turf.

I swap into the G63 and do the same again. For 50 yards, until I slow right down. It just can’t hack it. In the Mercedes you leap around the cabin as the car crashes and thumps along, and you live in fear of pinching a tyre between a rim and the biting edge of a pothole until it punctures. That’s to be expected, really, given their vastly different rubber. Equip the G63 with a set of smaller wheels and the same tyres and you’ll get much of the way there, but it would never skate across this road with the deftness of the Octa.

In all fairness to the Mercedes, though, as we ventured further and further into the disused quarry, it went everywhere the Land Rover did. And it did so without ever feeling like it might get stuck, scaling the same rocky inclines and wading through the same deep pools. Ultimately, and on the roughest terrain, the Defender will go places the G63 never could, but I was amazed at how far the Mercedes would plug along on its low-profile summer tyres.

I’d like to spend the entire day slithering around this old quarry and blasting along that approach road, but we ought to find how these machines compare on the highway. A favourite of ours is just minutes away and the Mercedes will get its chance to fight back.

With its four fat Goodyears finally in contact with the smooth, sealed asphalt they so prefer, the G63 winds up its knockout blow, one balled fist flying through the air at the Octa. But it misses, and the impetus is too much, sending the G63 sprawling to all fours. The Land Rover continues on its way. The fact is, even on roads like these, the Mercedes doesn’t have anything like the Defender’s breadth of ability. Its steering is far less precise, it rides lumpily at low speeds, and it’ll understeer into a corner and oversteer on the way out without you meaning to agitate it at all.

On the other hand, its hydraulic suspension does contain the vast weight of the body rather well, so it doesn’t list like a torpedoed frigate in corners nor dip or raise its nose as you switch between the pedals. That means you can at least hustle it along a mountain road with a degree of confidence. Try to unleash the mighty force of its AMG V8 all at once, though, particularly in a lower gear, and you’ll feel like you’re riding a mechanical bull, clinging on for dear life.

The Land Rover isn’t overwhelmed by its own power in anything like the same way. It too keeps body roll to a minimum, but it rides so brilliantly you would swear the entire road had been resurfaced end to end in the few minutes it took to switch from one car to the other. This is an even more faithful ally along this sort of road, an easier machine by far to pick up and fling across a landscape.

Those off-road tyres are the limiting factor on the road, making the steering just a little woolier than you might like, running out of cornering grip a fraction sooner. But actually, I think that’s part of the charm. Gravel tyres on an asphalt surface give wonderfully progressive breakaway characteristics, whether we’re talking Defender Octas or 911 Dakars, and if you really want sharper steering and more outright grip on the highway, Land Rover will do you set of road tyres instead.

Being as tall and heavy as they are, both cars have the same tendency to split the process of entering a corner into three separate, distinct, disjointed phases. First you turn the wheel and sense the tyres turn against the road surface, then you feel the weight shift to the outside rear corner, and then you feel the car turn in. It’s that middle phase, as all that mass, so high off the road, lurches across your back that can spook you at first. They both do it. The trick is to be more deliberate with your inputs, compress the outer springs more forcefully, and trust that the momentum won’t take the car away from you. Driven that way, both the G63 and Defender become far more confidence-inspiring machines.

I was so impressed by the Octa. Mostly it’s the air-sprung hydraulic suspension – Land Rover calls it 6D Dynamics, without revealing exactly what the fourth, fifth and sixth dimensions actually are, damn them – that means it rides so smoothly on the road and glides so effortlessly across a broken surface at speed. But the rest of the package is excellent too, from the potent powertrain to the unflinching solidity of the body structure.

The Mercedes, meanwhile, is in a constant battle with itself. The G-Class is the ultimate off-roader at heart – a body-on-frame, live rear axle utility vehicle, but forced here to be athletic, like Orwell’s Boxer the carthorse lining up for the Grand National. And summer tyres and hydraulically connected suspension can only do so much.

If there is one great contrast between these two machines, it is that the Mercedes can never say quite what it’s built for, while the Land Rover has no doubt. It comes down to purpose, like it so often does, and the car with the clearer purpose is the winner by a distance.

And yet, the Land Rover is not the one that will turn heads in the street, show up in music videos or get chequebooks flapping in quite the same way. Whether it’s the sort of car you like or not, the G63 does have a certain star quality. It most definitely has its charms as well. But allow your head to overrule your heart for just a moment and it’s the Octa that comes flying by, and at one hell of a lick.

Photography by Mark Riccioni