Mercedes-Benz AMG GT vs BMW Z4

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.

The Z4 didn’t make me feel like Peirce Brosnan’s 007. It’s way too serious – a proper gritty reboot. Maybe it’s meant for Daniel Craig. Either way, its brave design makes it one of the best-looking BMWs of recent memory, and it’s a tech- and comfort-fest that the Bavarian automaker should be proud of. I just wish it was a smidge more fun behind the wheel.

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 Z4 is a sight to behold. It’s brave, especially for a BMW, it even betrays the brand’s strongest styling pillars, making its own way with its more horizontal grille design, flat body and curved out rear.

It’s more than that, though. In black, this car looks sinister, brooding. The more you look at it, the more you notice tiny details - the scooped-out sides, or the way the entire rear seems to flick up into the integrated spoiler. I couldn’t get enough of staring at it – it manages to look even better with the roof down.

That’s probably when it hit me. To my eyes, at least, this is the most stunning BMW in years. Sure, the X7 is a sight to behold due to its sheer dimensions and borderline offensive grille, but the Z4 is the opposite. It’s subtle, it hides its details away in its silhouette.

It’s designer, Calvin Luk (an Australian no less), was inspired at least in part by the Z8 – another Brosnan bond car – and you can see the Fisker design reflected in the Z4’s low, flat grille and almost bulbous rear.

Inside, sadly, the Z4’s strong design doesn’t quite play out. There’s no wily Fisker touches here, just a standard set of BMW switchgear. While it all works well, it just dumbs down the Z4’s character.

The big, chunky steering wheel in particular is a let-down. It’s the same wheel that sits in the brand’s X5 SUV, and it feels right there, but not here in a convertible where you’re so close to the ground. A smaller wheel would not only suit this car better, it would make it feel just a smidge more alive. I miss the three-spoke M sport wheel from previous-generation BMW cars.

I do like the dash, which is seemly carved from rhomboid shapes - a theme that rolls into the doors, screens, and vents elegantly. I’m normally not a fan of gloss plastics and chrome touches, but in the Z4 they’re all tastefully applied.

The seats, too, are lovely. I’m not sure about the contrast bright-red leather our car came with, but they’re nice and close to the ground and have excellent trim that you seem to sink into just enough to be comfortable and sporty all at once.

It’s a slick place to be, I just wish it felt less like you were at the helm of an SUV and more like you were driving something that looks this damn good.

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.

The Z4 is a convertible, so it’s naturally compromised on space. As far as convertibles go though, you’ll be hard pressed to find one you can fit more stuff into.

The Z4 is wide - the same width, in fact, as a 5 Series - and this carries into the cabin. There are only two seats, but those seats are wide, and occupants will find themselves with luxurious amounts of airspace for their arms, as well as excellent leather-trimmed and padded surfaces for landing elbows on.

Legroom is also great, as the seats have a surprising amount of rail-travel on them, so that even taller folk won’t struggle to fit their limbs in.

A genuinely impressive characteristic of the Z4 is much head room there it is. Despite its low-slung looks from the outside, the roof towers over my 182cm tall head when I’m inside, so this isn’t one of those convertibles that feels like braking too hard might simply decapitate those above six-foot tall.

In terms of storage areas you get some long but shallow trenches in the doors, a bay with connection ports and a Qi wireless charging pad under the air-conditioning controls, a glovebox (hey, not all convertibles have them) and a trick centre console that houses two deep cupholders inside.

There’s also a netted shelf behind the seats that could fit small bags, and given the length of the cabin, you could even fit laptops and the like behind the seats provided you haven’t used the full extent of the seat’s rearward movement.

The boot is deep, wide and long for a drop-top, and offers a total of 281-litres which is more than some popular hatchbacks. It even offers tie-down points and netting either side. To top it off, the fabric roof folds away into its own compartment, so the boot space is unaffected if you choose to drop the lid.

For a convertible – the Z4 is a practicality wizard.

The Z4 isn’t cheap, but it plays in a field of expensive Deutsche drop-tops. Our car was the mid-spec 30i which comes in at an MSRP of $104,900 (before on-road costs).

For that you’ll get a more highly tuned version of the base 20i’s four-cylinder turbocharged engine, producing 190kW/400Nm, 19-inch alloy wheels, M Sport brakes, Adaptive M suspension, and adaptive LED headlights.

That’s on top of the already impressively-specified 20i’s kit which includes dual 10.25-inch screens – one for the multimedia functions, the other as a digital dashboard, a head-up display, full Vernasca leather interior trim, auto-dimming rearview mirror, power adjustable and heated front seats with memory function, dual-zone climate control, 10-speaker 205W stereo, a Qi wireless charging pad, and adaptive cruise control as part of a marginally upgraded safety package (more on that in the safety section).

It’s a pretty plush set of equipment, although a challenging value proposition as the almost-as-well-equipped 20i starts from $84,900, a full $20k cheaper.

Rivals for this 30i model? You’ve got the soon-to-be-discontinued Mercedes-Benz SLC300 ($102,500), all-wheel drive Audi TT S quattro ($105,661), and, at a stretch, the entry-level Porsche Boxster ($122,960).

Of course, being a premium European car, there is an extensive options list. Our car was fitted with the excellent and probably-worth-the-money M Sport differential ($2400), as well as the rudely priced M seat belts (literally just the M pattern embroidered in - $560!) and interior ambient lighting package (lovely, perhaps not worth $550).

The Z4 is only offered in five colours, three of which – including our car’s Black Sapphire – come at a cost of $2000. The red interior, surprisingly, is a no-cost option.

If you’re keeping track that brings the car you’re looking at here to $110,410. Not cheap, and it doesn’t have six-cylinders - but given its other attributes explored later in this review, the fact that it still manages to undercut an entry-level Boxster is actually reasonable.

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.

Welcome to the age of ridiculously powered four-cylinder turbo engines. Despite a capacity of just 2.0-litres, the engine in the Z4 30i produces a whopping 190kW/400Nm.

That’s probably enough for a car this size. I’m keen to drive the six-cylinder, but surprisingly it seems to offer diminishing returns for extra cylinders offering a 60kW/100Nm power boost for an extra $20,000. Perhaps a six-cylinder is the way to go in a BMW, and given this car’s other seriously sporty attributes, it might be the only way to make it a bit more… fun. More on that in the driving section.

All Z4s are rear-wheel drive, using an eight-speed torque converter automatic. Sorry, no option for a manual this time around.

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.

It’s claimed that the Z4 will drink just 6.5 litres per 100 kilometres on the official combined cycle test, but I found that sticking my foot in occasionally resulted in a slightly more realistic sounding figure of 8.4L/100km.

That’s still a great fuel consumption number for a car like this, and perhaps one of the strongest benefits of having just four cylinders.

A discerning vehicle, the Z4 will drink nothing less than the best-quality 98RON unleaded to fill its 52-litre tank.

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.

A car that looks this good better live up to the promise behind the wheel, right?

For the most part, the 30i does, but it’s a victim of its own performance credentials and luxuriousness.

See, a drop-top should be fun-packed, you should feel close to the road, connected. Sadly, a combination Z4’s excellent suspension and not-so-excellent SUV-like interior separates you too much from the surface below.

An advantage, of course, is the refinement on offer. The Z4 is easily one of the quietest, most refined convertibles I’ve ever driven, but it’s a little too insulated.

I can’t help but feel like it’s all business and no pleasure. It feels a little more like I should be cruising to work on the autobahn and a little less like I should be flinging it around corners on a tight B-road.

It feels almost wrong to drive it in a T-shirt. It’s serious and doesn’t want you to mess around, it wants you to wear a suit and tie.

This grand-tourer style feel is one that will keep a lot of buyers in the premium space happy, but I’m of the opinion that BMW will have that segment well and truly covered by the new 8 Series. If the budget allows.

Regardless, the 30i’s four-cyl engine feels like any six-cylinder would have a few years ago. It’s got a surge to it in the straights that’s quite satisfying, and it responds via the exhaust with an angry tone that makes it feel a little more alive, especially with the roof down.

This feeling was all helped along by our car’s M active differential which simply won’t let the fat tyres at the rear slide unless you’ve got high-speeds and loads of tarmac to play with – for better or worse.

The Z4 also has ‘variable sport steering’ which reacts to the car’s speed and position of the wheels to adjust the input ratio. It’s good when you’re at speed, but the weight and response of the steering can make the Z4 feel bigger than it actually is at lower speeds. 

The suspension is firm, and can be a little bouncy over rough surfaces, but seems well suited to the Z4’s chassis.

Other than those notable characteristics you’ll find that the Z4 is wonderfully tuned in terms of its inputs, everything is slick and smooth, suited perfectly for long meandering drives.

Convertibles and safety don’t often fall in the same sentence, unless its one where a concerned relative is trying to convince you not to buy one.

In any case, the Z4 benefits from four airbags (dual front and dual side), as well as the expected electronic stability controls. That optional M Sport differential will have the added bonus of preventing any unexpected slip and slide at the rear.

On the active side the Z4 gets ‘Driving Assistant’ which includes forward collision warning (FCW), lane departure warning (LDW), rear cross traffic alert (RCTA), and rear collision warning. The 30i grade also gets 'active cruise control with stop & go' which allows for full auto emergency braking (AEB) with pedestrian and cyclist detection. Not on the spec sheet, but apparently present in the car I drove was some form of traffic sign recognition (TSR) and lane keep assist (LKAS).

A nice high-res reversing camera displayed on the massive touchscreen is a welcome standard addition.

Considering the meagre safety specification of most convertible cars, the Z4 30i shines with a half-way decent active safety suite. But you can forget ISOFIX child-seat anchor points. There aren't any. 

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.

If recent quotes are anything to go by BMW is set to stick by its lacklustre three-year unlimited kilometre warranty, as it says its customers simply aren’t interested in five years (or longer) when it comes to warranty coverage.

It’s a shame, as even Volkswagen has upped its warranty to five years, and Mercedes has considered a 10-year coverage plan in the past.

In terms of servicing, there are two fixed-price plans available – the suspiciously cheap ‘Basic’ plan which comes at a cost of $1373 for five years (or $274.60 per year) and the more realistic-sounding ‘Plus’ which costs $3934 over five years (or $786.80 per year).

Like every other BMW, the Z4’s computer tells you when its service time: how often it needs maintenance will depend on how often – and how hard – you drive it.