Audi RS Q8 vs Mercedes-AMG GLC63

What's the difference?

The Audi RS Q8 is every bit as competent as it is striking to look at - and it’s plenty striking to look at. It surely won’t appeal to everyone, but if you’re in the market for a big, boisterous SUV, the Audi ticks plenty of boxes. 

And if you happen to be in the market for a Lamborghini Urus, be sure to drive this before signing on the dotted line...

Obviously, I had nothing to worry about. The GLC 63 S is the same boisterous, silly car I drove 18 months ago, just with a few new bits to improve the package. As ever, the GLC 63 S is all about the experience - big noise, huge grip but all in comfort with plenty of gadgets.

The only real issues are price, service pricing and the length of the warranty. The first two probably won't bother most owners and one hopes the third won't be problem, but it would be nice if the length was reflected in the price.

If you care about badge, it has impeccable credentials, the AMG stripes and that plate on the engine with the builder's name. They're good credentials. The GLC 63 S has some very determined and capable competition, but none of them blend the speed, overall comfort and sheer sensory silliness of the AMG.

It looks plenty striking, the RS Q8, especially dressed in the bright green paint work of that harks to its Lamborghini sibling.

There are the massive black-on silver alloys, the bright red brake calipers the size of dinner plates, and the body creases that bulge out over the rear arches like a 1950s’ pin-up model. All of which looks great.

Step around to the rear of the vehicle and you’re greeted with twin exhaust exits bookending a massive textured diffuser, a single light LED that splits the multi-globe LEDS, and the slick roof spoiler.

It’s the front-on view, though, that’s the most imposing, with a black meshed grille that looks as big as a hatchback, two LED-filled slimline headlights and massive side venting.

Climb into the cabin and you’re met by a wall of leather and technology, not to mention a sense of immense space.

Everything is digital and touch activated, of course, and yet it doesn’t feel garish and overdone.

As before, the GLC 63 S comes in wagon and couple bodystyles. Little has changed, with just the usual tweaked front and rear bumpers and mildly redesigned headlights.

All the good bits have remained, like the 'Panamericana' grille from the AMG GT monsters, the jet wing-inspired front bumper and plenty of open space to feed the radiators and intercoolers.

Neither the wagon nor coupe is a pretty machine, but no mid-size SUV is much of an oil painting, with the exception of the Jaguar F-Pace.

The 'Night Package' is still a standard inclusion, blacking out various bits and pieces and looking good when allied with the dark alloys. They both look tough, though, which is classic AMG DNA.

Inside is pretty much the same as before, with just two obvious changes. The new Alcantara-trimmed steering wheel, again from the AMG GT, and also on the C 63 S, joins the party with a more expensive look and feel.

And the new MBUX screen is wider and looks much more at home in a $165,000-plus car. It's still a bit old-feeling, but the digital dash adds a bit of techno-style while the garish speaker covers don't.

Very damn practical, actually. Which is no great surprise, given the size of the thing, but still impressive when you consider the performance it can conjure. 

It stretches more than 5.0m in length, and those dimensions translate to an absolutely massive cabin, which is actually most noticeable in the backseat, which is gigantic. You can essentially park an Audi A1 back there, such is the space on offer, but you’ll also find two USB ports, a 12-volt power outlet, digital air-con controls and leather as far as the eye can see.

There are two cupholders up front, another two in the pull down divider in the rear, and bottle holders in all doors, as well as ISOFIX attachment points for child seats. 

Storage? Well, there’s lots… The backseat slides forwards or backwards to prioritise space for either passengers or cargo, unlocking 605 litres of luggage room, but with them folded flat, the RS Q8 will deliver 1755L of space. Which is a lot.

A family of four will love any GLC. The wagon's extra headroom over the coupe is useful if not life-changing, while the knee, leg and foot room are generous. Front seat passengers enjoy comfortable seating as long as you're not too keen on pudding.

Underneath, the upward sweep of the centre console is a pair of cupholders and a wireless charging Qi pad that will fit larger phones. Under the split armrest is a small but handy console bin, inside which you'll find USB-C ports.

Two more USB-C ports in the rear join a 12-volt socket and there are also climate controls for the rear seat passengers. The centre armrest pops open with a shallow, carpet-lined tray and two cupholders pop out the front. Each of the four doors has a bottle holder, too.

The boot space is unchanged for each bodystyle - 550/1600 litres for the wagon and 500/1400 litres for the coupe. Both have high loading lips, which is something to consider if you're hauling heavy things about or have trouble lifting items to a reasonable height.

As before, we get two bodystyles and the high(er) performance version, the GLC 63 S (a 'base' GLC 63 is available in other markets). Mercedes followed everyone else's lead and realised nobody would buy the skim milk version.

Unfortunately, that translates to the highest sticker price of the three, with the wagon coming in at $164,900, and the coupe at $171,900, before on-road costs.

That doesn't seem to hurt Mercedes too much with other cars in the range, but it's a significant difference. Incidentally, both prices are up by about $3000.

It's loaded, though - 21-inch wheels, multi-zone climate control, air suspension with dynamic dampers, electric and heated front seats, active cruise control, head-up display, reversing camera, around-view cameras, sat nav, front and rear parking sensors, keyless entry and start, electric tailgate, Nappa leather and wood trim, active LED headlights, auto wipers, auto parking, roof rails, sunroof, DVD player, and TV tuner, but no spare tyre, just a repair kit.

A Burmester-branded 13-speaker sound system is powered by Mercedes' spangly MBUX system on a new 10-inch touchscreen, which is much nicer than the old software and hardware combo.

MBUX offers deeper integration with the car's systems. The 'Themes' function is like a series of shortcuts to set the car up for a particular mood, but let's face it, most GLC 63 S drivers are just going to find the 'Race' function and go for it.

MBUX also has Apple CarPlay and Android Auto, but via USB only.

The Audi RS Q8’s 4.0-litre twin-turbo V8 produces a monstrous 441kW and 800Nm, sent to all four wheels via an eight-speed triptronic automatic.

At more than two tonnes, it’s a lot of car, but that’s also a lot of power, and so the go-fast SUV can produce a cracking sprint to 100km/h of just 3.8 seconds. 

The RS Q8 is also equipped with a 48-volt mild hybrid system that is ostensibly designed to lower fuel use, but is actually more useful at plugging any turbo holes when you really plant your foot.

An AMG 4.0-litre twin-turbo V8 brings the thunder, with a massive 375kW and 700Nm of torque. That's plugged into a nine-speed MCT (multi-clutch as opposed to twin-clutch) transmission and Merc's '4Matic+' all-wheel drive system.

With all that power and grip, you'll crack the ton in a supercar-baiting 3.8 seconds. One little point to note is the engine has active mounts.

Should you fancy turning your tinny into a landspeedboat, you can tow up to 2000kg for a braked trailer, and 750kg unbraked.

For every action there is an equal and opposite reaction, right? Well the reaction to all that power is a whole lot of fuel use. 

Audi reckons the RS Q8 will sip 12.1L per 100km on the combined cycle, but we suspect that’s wishful thinking. It will also reportedly emit between around 276g/km of C02.

The big SUV is fitted with a huge 85-litre tank.

Mercedes reckons you'll get 12.2L/100km on the combined cycle which seems laughable at first and then you see what it actually does. To be fair, the car I drove on the launch copped a hammering and was hovering around the 17.0L/100km, with the start-stop and coasting functions playing only cameo roles.

How do you describe the drive experience of the RS Q8? Utterly, utterly surprising.

I’ll give you an example. You approach the hulking SUV, check out its massive alloys wrapped in performance rubber, and you know - just know - that it will ride like a broken billycart on anything but the most silky smooth of road surfaces. 

And yet, it doesn’t. Aided by its clever air suspension (which drops the ride height by 90mm when switching between Off-Road and Dynamic modes), the RS Q8 positively glides ever dodgy road surfaces, stifling lumps and bumps with surprising aplomb. 

So then you think, ok, we’re set up for compliance, so this big behemoth will go around corners with all the dynamism of a spilled bowl of cereal. 

But again, it doesn’t. In fact, the Audi RS Q8 attacks corners with incredible stiffness, the active anti-roll systems weaving their dark magic to keep the towering SUV straight and true, and with barely a hint of body roll.

The grip is ferocious (we’re yet to find its outer limits) and even the steering feels more direct and communicative than in other smaller, ostensibly sportier Audis. 

The result is a tech-heavy spaceship that’s surprisingly easy at slow speeds, and quiet too, even over rough roads. But one that can also activate warp speed at will, leaving smaller cars in its considerable wake on the right stretch of road. 

Downsides? It’s not quite willing to pounce off the line. Sure, it makes up for it in the long haul, but there is a noticeable moment of hesitation, almost as though it’s contemplating its considerably weight, before it finally lunges forward. 

It’s also so competent, so efficient, that it can leave you feeling a little detached from behind the wheel, or like the Audi is doing the heavy lifting for you. 

Like any V8-powered AMG, the twin-turbo engine absolutely dominates the GLC 63 S. Even at walking speeds you can feel the serious firepower on offer, just a flex of your ankle away.

The figures are colossal - 375kW (over 500 horsepower) and 700Nm pushing around two tonnes of mid-sized SUV. Its famed bark is bettered only by Jaguar's completely unhinged, and surely borderline illegal, 5.0-litre supercharged V8.

You need to know you've got plenty of tech underneath you to make this stick to the road. The 21-inch alloys are wrapped in 265/40s at the front and 295/30s at the back, Continental Cross Contacts if you're interested.

They should - and would - ruin the ride, but the standard fitment of air suspension means that in normal driving, the GLC 63 S is firm but comfortable. A BMW X3 M is much harder, especially at the rear, going without the complex and heavier air set-up.

The air suspension is probably the pivotal piece of chassis tech that makes this car so versatile. While it's got driving modes up the wazoo - including the new 'Slippery' mode - it's a perfectly agreeable daily driver.

Leave it in comfort, accept that it has a firm ride and you're in good shape for the school run or the commute. You just sail along on a light throttle because there is virtually no turbo lag.

Whack it in Race and you can attack your favourite empty, bendy road with all the grip you could ever need.

The steering is remarkably light and direct for such a chunker and the optional carbon ceramic brakes were never bothered by what I could throw at them.

The V8 roars and spits and crackles, the gearbox shifting seamlessly up and down through the ratios. It's blissfully silly.

In a way, it's a velvet fist in an iron glove - comfortable inside but happy to headbutt the horizon with little provocation.

I'd prefer it if the transmission was a bit more decisive on slow speed shifts and you'll have to prepare yourself for a lot of wearying road noise on long trips. The latter is the price you pay for a ton of grip.

All GLCs have nine airbags, ABS, stability and traction controls, traffic sign recognition, around-view cameras, reversing camera, rear cross traffic alert, blind spot monitor, forward AEB, forward collision warning and tyre pressure monitoring.

There are also three top-tether mounts and two ISOFIX points.

The GLC scored a maximum five ANCAP stars in January 2016.

All Audi’s are covered by a three year, unlimited kilometre warranty, and require annual servicing. Audi will allow you to prepay the first five years of service costs for $4060.

Mercedes Benz offers a three year/unlimited kilometre warranty with roadside assist which is not really up to scratch for a premium brand. Yes, the cars are complex but they're also expensive, so the investment should come with a commensurate warranty.

Service intervals are generous at 12 months/20,000km (as opposed to the 25,000km of other GLCs) and the capped price servicing means you'll know what you're paying.

Mercedes offers you the choice of an up-front payment or pay-as-you-go. Upfront ranges from $4050 for three services, $6100 for four, and $6850 for five.

If you go with PAYG, three services is a hefty $5000. Basically, each service is at least a grand when averaged out over time and that's pricey.

Service inclusions differ between your chosen method, but only slightly. The pricing includes filters, oil and, unusually, spark plugs and brake fluid, but that's small comfort.