Mercedes-Benz AMG GT vs KTM X-Bow

What's the difference?

The GT63 4Matic+ is a breathtaking example of everything that Mercedes-Benz and AMG are.

Ferociously fast, incredibly agile and superbly sophisticated, it should be on anybody’s shortlist, if that also includes a Porsche, Aston Martin, Maserati or even a Lamborghini. And it’s definitely much more than yesterday’s SLC ever was – for similar money in today’s terms, as it turns out.

But, around Tasmania’s glorious roads at least, the Mercedes-AMG lacks the ride comfort and road noise isolation to be a fully-rounded-out GT, and that’s a disappointment for a brand with such formidable history in making such cars.

Okay, so rain is not your friend. Neither is brutal sunshine, strong winds or any speed bump anywhere. There are probably a handful of times you'll want to drive it, and when you do you will definitely get hit in the face with rocks and bugs, and spend most of your time wondering just how the hell this thing is legal.

And yet, we are hopelessly, head-over-heels in love with it. It's an absolute weapon on a track, a joy on anything even resembling a twisting road and it is one of the few genuinely unique cars on the road today. And the fact it exists at all is a cause for absolute celebration.

This is still clearly a Mercedes AMG GT coupe, like the 2014 C190 original, but a ground-up redesign sees it subtly yet significantly altered.

Some 270kg heavier than before, the larger-in-every-dimension body combines aluminium, steel, magnesium and fibre composite materials for improved rigidity and a lower centre of gravity. Length (4729mm) and wheelbase (2700mm) have been stretched by 177mm and 70mm respectively. Width (1984mm) and height (1352mm) are also up.

The nose treatment is similar to before, especially with the bulgy bonnet and signature vertical slatted grille fitted. These, combined with the LED digital headlight shape effect, is reminiscent of, but far-better executed than, the goofy-looking MG5’s face.

Underneath, it's an all-new platform shared with the SL, with the rear transaxle of the old car replaced by a permanent AWD system, leading from 46:54 front/rear weight distribution to 50:50 as a result.

That aggressive, exaggerated cab-backward/ultra-long bonnet silhouette that visually connected it with the SLS gives way to more-conventional and practical coupe proportions that is striking if not especially original, since they do look quite 911-esque. Along with the longer wheelbase and wider tracks, the result allows for two small rear seats to be fitted, while liftback cargo access remains.

Similarly, in the name of way-more usable interior packaging, Mercedes-AMG says it pushed the driving position nearly 180mm forward compared to the previous GT. Let’s see what that all looks like inside.

The X-Bow R is built for purpose in the most wonderful of ways. From the visible suspension components to the rocket-style exhausts, to the stripped-bare interior, it's fairly obvious that form came a distant second to function in the X-Bow's design process.

And, for us at least, that's a tremendous thing. It looks raw and visceral, and a bit like Harvey Dent post-fire - you can see all the normally hidden components doing their thing. It's mesmerising.

The first impression inside is that of space, despite the falling roofline and coupe-like upsweep of the side windows and you look back. While, again, similar to a 911s, a kink at the door gives the GT a unique character.

Even larger people will appreciate the generous amounts of room up front, with space to stretch, sat in sumptuously comfy bucket seats. Note that the standard ones are better than the racier but firmer Sports versions.

The driving position is perfect, ahead of a dashboard that is very typical modern Mercedes in appearance and layout.

To that end, the tablet-style integrated touchscreen (11.9 inches) is clear, fast and intuitive once time is taken to learn it. And points are also won for the multi-configurable electronic instrumentation, that allows for a variety of screens, including track, classic and minimalist views.

The trademark turbine air vents, the quite beautiful material and trim finishes and just the general solid feel are further typical contemporary Mercedes cabin treatments, as are the excellent ventilation and ample storage options.

And while rear vision isn't great, that's what cameras are for. It's all pretty much on brand.

It is a shame, given how elevated the Mercedes-AMG engineering is underneath, that the GT’s interior look and ambience is so similar to those of a (albeit higher-spec) C-Class or GLE. It's simply not as special as some of the company’s previous sports cars.

More annoyingly, the ride is too firm and bumpy for a GT, and this has the unhappy effect of provoking random rattly trim sounds within the cabin. It’s a bit like scrunched-up cellophane. In a $420K (as tested) Merc, that’s very disappointing, especially as it can be heard over the copious amount of road and tyre noise droning through, particularly on coarser bitumen surfaces.

Further back, the rear seat is strictly two-plus-two, and nobody over 150cm tall is recommended to travel there by Mercedes itself. That sloping roofline is the culprit. That said, brief trips with a bowed head are possible, as the fixed cushions and split-folding backrests are actually surprisingly comfy. But only for short journeys. Kids should love it though, and the second row does open up the GT’s usefulness enormously.

As does a near-doubling of the AMG’s cargo capacity, jumping 146 litres to 321L with backrests erect, to a whopping 675L (+325L) in two-seater mode. The flat floor is accessed via a large electrically-operated liftback door, offering quite a large aperture for easy loading/unloading.

Having no spare wheel helps here, with a tyre inflation kit included in lieu of that.

Meanwhile, at the front, under the bonnet, things have definitely changed for the better as well.

Short answer? It's not. People are unlikely to test drive an X-Bow R and start looking for cupholders and storage space, but if they did, it wouldn't take long.

Aside from the twin seats, a four-point racing harness, a high-mounted gearshift, a pull-lever handbrake, and detachable steering wheel, the cabin is as bare as Old Mother Hubbard's cupboard.

Luggage space is limited to what you can carry in your pockets (though wearing cargo pants will help) and even getting in and out of the thing takes some fleet-footed antics. With no doors you need to literally jump in. And the side sills are only rated to 120kg, so heavier types will need to avoid stepping on them at all, and instead attempt a kind of running leap into the cockpit.

Keen readers of this site will recognise this as the area where we outline the many and varied features that come along with a normal new car purchase, but that's just not going to work this time. In fact, it'll be considerably easier to talk about what's missing, so let's start with the obvious: doors, windows, roof, windscreen. All conspicuously absent from this weird and utterly wonderful X-Bow.

Inside, you'll find two thinly (and we mean thin - we've seen thicker contact lenses) padded seats fixed into the tub. You'll also find push-button start, a digital screen reminiscent of those found on motorbikes (KTM is an Austrian-based motorcycle company, after all) and a pedal box that slides backward and forwards to offset the height of the pilot. Oh, and that steering wheel can pop off to make getting in and out easier.

Climate control? Nope. Stereo? Nope. Proximity unlocking? Well, kind of. With no doors, you'll always find it unlocked when you enter its proximity. Does that count?

But what it does have is a turbocharged two-litre engine. And in a car that weighs a sprightly 790kg, that means it's quick, pulling like a rabid sled dog in every gear, rear tyres chirping with every change.

There’s a plaque signifying which engineer “handcrafted” the GT’s engine – in this case, the famous M177 in 3982cc, 4.0-litre twin-turbo intercooled V8 petrol guise.

Delivering 430kW of power at 6500rpm and 800Nm of torque from 2500-4500rpm, it sends drive to all four wheels via a nine-speed multi-clutch transmission (dubbed MCT in AMG-speak), catapulting the GT63 4Matic+ from 0-100km/h in just 3.2 seconds, on the way to a top speed of 315km/h.

How does it do that?

With AWD, the GT is now nearly 15 per cent heavier than before, but it still manages a punchy 218kW/tonne. Active aerodynamics over, inside and under a more-rigid body structure also helps.

The AMG 4Matic+ AWD system goes from 50/50 front/rear, to 100 per cent rear, variable torque distribution according to conditions and settings, and backed up by an electronic limited-slip differential. Among the many driving settings are Race Start, Drift Mode and good-old Comfort, if it all becomes too much.

Also keeping all that performance in check is a high-performance composite brake setup with improved cooling for faster responses.

Interlinked active roll bars improve body control, the five-link independent suspension features adaptive dampers for a softer ride.

And, as for that 4WS tech, the rear wheels steer opposite to the fronts at up to 100km/h (by some 2.5 degrees) for tighter and tidier handling, or 0.7 degrees in the same direction above 100, for greater stability and road-holding.

Its effect on the way this near-two-tonne coupe zigs and zags around corners is something you need to experience to really appreciate.

The X-Bow R's power comes from an Audi-sourced, turbocharged 2.0-litre engine, paired with a VW Group six-speed manual transmission (and one of the stubbiest gearsticks in existence). That mid-mounted marvel produces 220kW at 6300rpm and 400Nm at 3300rpm, and ships it off to the rear tyres with the assistance of a Drexler mechanical limited-slip differential.

Thanks to its lithe and lightweight body, that's enough to propel the X-Bow R from 0-100km/h in a blistering 3.9 seconds, and on to a top speed of 230km/h.

Actually, the GT’s economy isn’t horrendous considering how fast it can go.

Even blasting a few times around beckoning country roads, we managed an indicated 13.0L/100km, which is an improvement on what Mercedes-AMG says the GT averages the 14.6L/100km average that Mercedes-AMG officially states.

That translates to a carbon dioxide emissions rating of 334g/km.

Using 98 RON premium unleaded petrol, an average of just under 480km between refills of the 70L tank is possible. The urban run sees consumption rocket to 21.8L/100km (for just 321km of range), or 10.4 out on the highway run, meaning that over 670km is possible should you decide to drive in a docile manner.

KTM lists the X-Bow R's claimed/combined fuel figure at 8.3 litres per hundred kilometres (though we were managing mid-12s after an, ahem, very spirited test), with emissions pegged at 189 grams per kilometre.

The X-Bow R is also fitted with a 40-litre fuel tank, accessed via a side-mounted inlet. Instead of a fuel gauge, expect a digital reading showing how many litres you have left.

Nobody will drive the GT63 4Matic+ and think, ‘Oh, this is OK’, because its breadth of performance is phenomenal.

No matter which mode you're in, from Comfort through to track-tuned Race, the Mercedes-AMG blends forceful pace and commanding control without ever breaking a sweat.

Flex your right foot and the two-tonne coupe bounds into action like a giant on a mission, striding past posted speed limit signs in nanoseconds and way, way faster than the law will stand if diligence isn’t exercised.

And there’s no point relying on seat-of-your-pants sensations, either, because the chassis below embraces the road with an almost zealous devotion. Which is astounding, given how agile the four-wheel steering-enhanced handling is.

The 63’s super power is exactly that – it dulls your sense of speed. One tester admitted to exceeding 150km/h before noticing. An odd confession considering the sonic boombox that is the bi-turbo V8’s howl.

But jailbait performance is not even the 63’s most lingering joy. That would be its steering perfection, that delivers that rare trifecta of keenness, crispness and communication. The wheel feels eager and alive in your hands, even when powering between tight turns, backed up by sensational grip and control. How can a two-tonne GT handle so sharply?

Warm, dry roads were the order of the day, so we can’t tell you how the 4Matic+ permanent AWD system deals with wet or slippery surfaces, but the slick multi-clutch transmission, seamless torque-vectoring tech and sticky tyres more than cope with the 63’s formidable outputs.

So, that's the gushing part out the way, then.

Despite the adaptive dampers, rigid architecture and exquisitely sophisticated suspension, the ride is simply too stiff in Comfort mode, and downright jittery on some of the Tasmanian roads we tested on, for the 63 to be considered a true luxury grand tourer. It just isn't comfortable, luxurious or supple enough.

Plus, grippy as they are, the 21-inch wheels transmit too much road and tyre noise through to the cabin, meaning that the GT isn't as quiet as you'd hope. Add the aforementioned trim squeaks, and the expected cocooned silence isn’t always there.

The upshot is that the 63 possesses more of a sports car character than a luxury GT character. Great news if you're a 911 type buyer and are seeking a high-performance 2+2 alternative, but a disappointment if comfort and refinement are priorities.

Still, it is impossible not to be deeply moved by this Mercedes-AMG.

It couldn't be more Fast and Furious if it had Vin Diesel growling under its (non-existent) bonnet. We have technically driven faster cars, but we have never driven anything that feels quite so fast as this utterly insane X-Bow R.

Climb in, strap into the four-point harness and select first via the surprisingly easy-to-manage gearbox and clutch set up, and, at slow speeds, wrestle with the dead weight of the completely unassisted steering, and it's immediately clear that this is a driving experience like nothing else currently road-legal in Australia. Even at walking pace, the X-Bow R feels poised for an assault on the future, and it attracts attention on the road like nothing else we've ever driven.

Its road-scraping ride height and diminutive dimensions make tackling traffic an intimidating prospect, with regular hatchbacks suddenly taking on truck-like proportions and actual trucks now looking like passing planets. There's a constant concern that you're sitting well below the traditional blind spot, and that you could be crushed at any moment.

Combine all that with the bad weather that cursed our final day of testing, and the X-Bow R is all sorts of watery hell. It is truly homicidal in the wet, too, with the back end breaking grip at the slightest provocation. And the turbocharged 2.0-litre offers plenty of that.

But on a sunny day, and on the right road, it's pure driving bliss. The acceleration is brutal, the grip endless and the Audi sourced gearbox an absolute treat. And it pulls in every gear, tackling 35km/h corners in third and absolutely blasting out the other side.

Cornering is scalpel sharp, and the steering - so heavy at slow speeds - is light and efficient at pace, requiring only the most minuscule of movements to bite into a bend.

It is anything but perfect in the city, and even a light sprinkling of rain will have you seeking shelter (and a refund), but on the right road, on the right day, there are few if any cars that offer the kind of razor-sharp thrills and intoxicating excitement of KTM's monstrous X-Bow R.

Next to none. There is no ABS, traction or stability control. No airbags, powered steering or ISOFIX attachment points, either. If you break traction (which, in the wet, is more than a little bit likely) it'll be up to you to ensure you straighten up again. Helpfully, there's a ton of grip from the Michelin Super Sport tyres.

As part of the compliance program, Simply Sports Cars (the company responsible for introducing the X-Bow R) actually crash tested two cars in Europe, and raised the ride height by 10 millimetres. Oh, and there's now a seatbelt warning sign, too.

What’s the GT like to own?

Mercedes-Benz offers a five-year/unlimited km warranty, with five years of roadside assistance. This is average for most mainstream and luxury brands, but superior to most sports-car makers like Porsche and Lamborghini.

Intervals are every 12 months or 20,000km, and while no capped-priced servicing is offered on the GT, pre-paid three-, four- or five-year service plans are available, ranging from $5165, $7700 and $8665 respectively.

Big performance demands big maintenance bills, it seems.

The X-Bow R is covered by a two-year, unlimited-kilometre warranty, and while service prices aren't capped, Simply Sports Cars estimates an average serve cost at about $350.