2018 Mercedes-AMG GLC63 S Coupe performance review

It's more than a little ironic that thanks to AMG, a vehicle intended primarily to carry children now makes a noise apparently specifically designed to frighten them.

There's nothing pretty about the sound that escapes from the Mercedes-AMG GLC63's quad tailpipes; it's dirty, industrial, more Metallica than Mozart, but we suspect that's exactly how most buyers will want it.

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Performance SUVs are so hot right now, with mid-sizers particularly popular due to hitting the sweet spot between having the sought-after status and elevated driving position without the feeling of driving a city bus. The GLC43 is AMG's biggest seller locally so far in 2018, fighting it out with the Audi SQ5, Jaguar F-Pace 35t, Porsche Macan GTS and forth coming BMW X3 M40i.

In classic AMG style, it's now uppped the ante by squeezing the biggest possible engine between the GLC's front strut towers; in this case, the 4.0-litre twin-turbo V8 from the C63. As with its sedan sibling, the GLC63 is offered locally only in 375kW/700Nm 'S' guise.

Connected to the latest nine-speed wet-clutch automatic and all-wheel drive, the result is a claimed 3.8sec from 0-100km/h and an electronically limited top speed of 270km/h.

As you might gather from those figures, the performance is ferocious. The GLC63 uses AMG's new launch control, which replaces the old 'pull these paddles then this paddle' procedure with a simple 'squeeze brake, floor throttle, release brake' dance.

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To be honest, I kind of miss the old rigmarole; it always felt like you were doing something special and possibly a bit illicit by RACE START, like firing missiles from a submarine, but the new process is much simpler.

The system dials up just over 3000rpm, the engine straining and stuttering against a temporary limiter like a racehorse that's eager to leave the gates. Lift your left foot and it explodes forward with such ferocity that the floor mat in the passenger footwell curls backwards, possibly into the foetal position.

Unbelievably, the GLC struggles to match its claims due to excessive wheelspin; on Heathcote's slippery unprepped start line even giant Michelin Pilot Sport 4S tyres (265/40 front; 295/35 rear) are unable to contain the enormous grunt, slight corrective lock is required to keep Merc's monster mid-sizer pointing straight on the wilder launches. It's an impressive spectacle, but not quick, more than four seconds consistently ticking by before 100km/h is reached.

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The quickest figures of 3.92sec to 100km/h and a 12.05sec 400m sprint come by lifting from the brake as the revs are still building. On a grippier surface there's no doubt the GLC would hit its claims; it's tempting to continue experimenting with different launch rpms to find that elusive tenth but RACE START is a fairly brutal process and, let's face it, 3.92sec isn't too shabby.

What's particularly impressive is the GLC63's consistency; in eight of its nine runs it records a trap speed between 189.2-190.0km/h - no heat soak issues whatsoever.

For most buyers the review can end here: the GLC63 sounds great and is tremendously quick in a straight line. Throw in a premium interior, practical load space (550L of luggage space in the wagon, 500L in the Coupe) and all-important badge appeal and it's job done. The vast majority of these cars will never do anything more stressful than school and shopping runs, burbling through some of Australia's more affluent suburbs.

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However, should anyone stray into the woods one day, well, they're in for a big surprise, for the GLC63 is more entertaining in the bends than it has any right to be.

Don't expect miracles. This is still a heavy car (more than two tonnes with fuel and driver) with a high centre of gravity and sticking a twin-turbo V8 in it hasn't suddenly transformed it into a Cayman or even an A45.

Nonetheless, hitherto the very best performance SUVs have managed to drive about as well as a mid-level hot hatch - think Volkswagen Golf R - with most failing to even achieve that, but the GLC63 is the first we've driven (locally, at least) with the potential to transcend that analogy.

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Sending drive through the front wheels has corrupted the steering slightly compared to, say, a C63 sedan, however it's well weighted and the front end responds keenly. It resists understeer remarkably well - those super-wide high performance front tyres earn their keep - and displays excellent balance for something so large.

Key to its ability, though, is the use of the E63's constantly variable 4MATIC+ all-wheel drive. Rear-driven under most circumstances, power can be apportioned between the axles as the situation demands, while the rear electronically controlled limited-slip differential can also shift power left or right. The upshot is the ability to control cornering attitude with the throttle.

Whereas a tradition Haldex-based system, like that found in the A45 or RS3, requires patience on corner exit to prevent the front running wide under power, in the GLC63 gentle understeer can be neutralised with more power.

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Provoke it and it'll power oversteer like an Audi R8 before shuffling the drive forward to pull everything straight; it's not ballet, as there's a lot of momentum involved, but this unlikely adjustability makes the GLC63, dare I say it, fun. The nine-speed MCT auto also works well when left in drive, more often than not decisively picking the correct gear for the corner.

It's probably not as dynamically polished as a Porsche Macan Turbo - a back-to-back test is really required - but then the Porsche doesn't sound like a grizzly bear with a stomach ache. Nor can it match the AMG's in-gear punch. On an open, flowing road the GLC's weight is less of an issue and the way it covers ground is staggering.

Thankfully, this dynamic prowess isn't accompanied by a skateboard ride. On a typical country road it's busy, but whether it's due to a softer suspension tune or the fact you're further removed from the road occupants are isolated from the worst bumps and lumps. It's certainly more comfortable than the equivalent C63 S wagon and the rear seat is better, too, with more leg support and greater room.

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At $164,900 for the wagon and $171,900 for the Coupe, the GLC63 is expensive when you consider a Macan Turbo is $133,500 similarly powerful Jaguar F-Pace SVR will be $140,020.

That said, the options lists on both those cars tend to be expensive, whereas Mercedes has loaded local GLCs to the hilt, including Nappa leather trim, AMG performance steering wheel and seats, digital TV, Panamericana grille, rear diffuser and splitter, performance exhaust, 21-inch wheels and the blacked-out AMG Night Package.

Options are limited to three different wheels (titanium grey $1200; black forged $1700), carbon packs for the interior ($1490) and exterior ($4500) and carbon-ceramic brakes ($7500). Our test car had the latter and they are worth considering, partly because the stopper work extremely hard on a twisty road and partly because gold calipers look extremely cool.

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The Mercedes-AMG GLC63 S is a surprise packet; it's the closest we've come to sampling a truly engaging SUV. Given it's solely focused on on-road performance, perhaps that's not surprising, and whether it is good enough to best the likes of the new supercharged V8 Jaguar and 'Ring record-setting Alfa Romeo Stelvio Q remains to be seen.

What's certain is that based on this new AMG, the comparison test will be more entertaining that perhaps we initially expected. Everyone at MOTOR would still take a C63 S Estate every day of the week, however, for many buyers the GLC63's greater comfort, rear space and all-weather performance ability will be the clincher.

Simply put, whether you want to transport your children or frighten them, AMG's new SUV has you covered.

The Strip

Heathcote Dragway, 13˚C, dry
Driver: Scott Newman
*Manufacturer’s claim

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FAST FACTS
2018 Mercedes-AMG GLC63 S Coupe

BODY: 5-door, 5-seat hatch
DRIVE: all-wheel
ENGINE: 3982cc V8, DOHC, 32v, twin-turbo
POWER: 375kW @ 5500-6250rpm
TORQUE: 700Nm @ 1750-4500rpm
BORE/STROKE: 83.0mm x 92.0mm
COMPRESSION RATIO: 10.5:1
WEIGHT: 1945kg
POWER-TO-WEIGHT: 193kW/tonne
TRANSMISSION: 9-speed wet-clutch auto
SUSPENSION: multi-links, air springs, anti-roll bar (f/r)
L/W/H: 4745/1930/1585mm
WHEELBASE: 2873mm
STEERING: electrically-assisted rack-and-pinion
BRAKES: 402mm ventilated/drilled carbon-cermaic discs, 6-piston calipers (f); 360mm ventilated/drilled discs, single-piston calipers (r)
WHEELS: 21.0 x 9.5-inch (f); 21 x 10-inch (r)
TYRES: Michelin Pilot Sport 4S; 265/40 ZR21 (f); 295/35 ZR21 (r)
PRICE: $164,900 (wagon); $171,900 (coupe)

LIKE: Performance; surprisingly engaging; standard kit
DISLIKE: Pricey; thirsty; slight loss of steering precision

RATING: 4 out of 5 stars