Mercedes-Benz S450 vs Audi RS6

What's the difference?

Mercedes-Benz set out to restore the S-Class' place amongst the greatest sedans in the world.

In the heavily-optioned, near-$250K-plus S450 as well as the extended S450L at $300K as tested (the sweet spot of the range for now), we reckon the Germans have succeeded, pushing safety, comfort and technology boundaries, in a package that is true to the heritage of the series.

Tax-fuelled sky-high prices will certainly keep the S-Class niche in Australia, but the car is more than good enough to dominate its tiny corner of the upper-large luxury car sphere.

The best new car in the world? We reckon it's highly likely. Mission accomplished, Mercedes.

You’ll notice a number out of 10 on this review, you should ignore it.

Not only is it irrelevant because you can’t buy one, but the RS6 Avant GT isn’t a ‘brain’ car, it’s a ‘heart’ car. As much as a five-seat wagon can be, anyway.

Whether you think it’s overkill, overpriced, or overhyped, the GT is a celebration of a car that’s become such an icon for petrolheads. It’s also probably a marker for the end of an era, because we don’t see many V8 family cars getting about anymore.

Well done to Audi, the accounting team in particular, and if anyone who owns an Avant GT is willing to let me have another drive, my in-box is open. 

Or I’ll just keep an eye out.

Most Mercedes models have followed the Russian Doll-style cookie-cutter styling theme, and the heavy family look continues with the W223.

Still, the flush door handles do add a touch of Tesla-esque modernity, while the elegant silhouette and clean lines are in keeping with the luxury aspirations. Larger in every dimension compared to the old W222, the S450 is some 71mm-longer in wheelbase (3106mm) than before while the LWB's has stretched out by 51mm (3216mm), benefiting proportions as well as interior packaging.

AMG-branded wheels look sporty but – in the S450 at least – they're perhaps a tad too gangster. A set of flush alloys would give it a more-modern and techier appearance, in our opinion.

Overall, however, the S-Class ‘7' possesses the prerequisite richness of design. It isn't as bold and mould-breaking as models like the W116 were back in their day, but the styling is still a success.

By the way, the latest S-Class is the first Mercedes to employ the MRA2 longitudinal platform, which is rich in lightweight steels (50 per cent aluminium), is correspondingly stronger than before but also 60kg lighter.

With a drag co-efficiency rating as low as 0.22Cd on some overseas grades, the W223 is one of the most aerodynamic production vehicles in history.

“It looks like a toy car you’d get in a Kinder Surprise” was the first comment from my housemate upon seeing the $400K collector's item on wheels.

Harsh, but to anyone unfamiliar with the Audi 90 quattro IMSA GTO racer, there’s arguably too much going on with the RS6 Avant GT.

The red, grey and black decals, the chunky white 22-inch wheels, the flared and vented front fenders and the wing over the rear window… all of it is a lot to take in, but it’s very faithful to the IMSA car.

As pictured, the 90 quattro IMSA has the red around the bottom lip of the car, on the bonnet, and even its rear wind, the same as the red on the rear of the Avant GT.

Some of the black at the front of the car, where the bonnet and fenders are, is just exposed carbon-fibre rather than a black decal.

Short of the sponsors and racing numbers, the Avant GT does a fabulous job of paying homage to the 1989 race car. It just means you’re going to be the centre of attention anywhere you drive. Or park.

On that note, an alternative paint and graphic scheme in 'Mythos Black' (this car is 'Arkona White') was available to customers and is decidedly more ‘under the radar’. You have to wonder, though, if you opted for the subtle version of a car that pays homage to a fire-breathing IMSA car, would you feel like you took the coward's option?

Besides, you’re either keeping this car in some kind of temperature-controlled bubble, or (hopefully) spending most of your time around it in the driver’s seat. From there, you don’t have to grapple with the question of garishness.

The interior is, while elevated past standard RS6 vibes, a lot more subtle. Dark materials of microfibre, carbon, leather and the smudge-prone piano black (an Audi favourite) are joined by a relatively restrained serving of red in the contrast stitching and seatbelts.

For the beginning of our day with the S-Class, we were chauffeured from home to a mansion in Kew, a blue-chip Melbourne suburb. Our heavily-optioned S450L featured most of the aforementioned extras – including the Business Class Package and Rear Entertainment Package – and the experience was predictably, sumptuously memorable.

Reclining individual rear seats with easy-reach tablets, armrests offering access to all multimedia and available climatised and massaging cushions and backrests... we're no longer in our normal ride, Toto.

Yet, all these trinkets and gizmos are mere add-ons, that can turn a stretched Caprice into a flash hen's night carriage if enough money and glitz is thrown at it.

No, the new S-Class must impress in an altogether less tangible and more philosophical manner, involving all the senses, and not just what we see, hear and touch. It must appeal beyond the superficial. Otherwise, it is not a large Mercedes-Benz luxury sedan in the classic manner.

This is a Herculean task for the Stuttgart designers and engineers. By and large, though, the Three-Pointed Star has succeeded in achieving something special.

In its perception of peerless quality and engineering, the W223 is striving to move forward and look back simultaneously to the glory days of the seminal W126 (1980-1991). This is through meshing traditional virtues like solidity and quality materials while dazzling its passengers with technology that is still friendly enough to want to enhance your experience.

You can sink into the soft lounge seats, watch the world pass by silently outside and never be aware of the road underneath or the engine ahead. Double glazing, exquisite and aromatic fabrics and materials and lush tactile surfaces work their magic inside the car, while an airtight and aero body, solid platform, air suspension and a muted yet muscular powertrain all do their thing underneath. The atmosphere is special and rarefied. That's what an S-Class needs to be and that's what is happening in our $299,000 (as tested) S450L.

The same more-or-less applies up front, as the same trim, leather, wood and technology surrounds the driver and passenger. The spectre of the car that is surely The Car of the Last Decade – Tesla's Model S – is evident in the portrait touchscreen and sparse, almost wallflower dashboard design and layout. No big imposing architectures here.

Yet, while the American upstart actually takes stuff away, the S-Class packs the cabin with subtle features that – like when the planes stopped flying last year and the birdsong subsequently returned – only become obvious once the cabin's design simplicity clears all the white noise for you to be in a better frame of mind to enjoy them.   

Take the haptic interface, for example, as it is perhaps the best we've experienced; the sense of well-being garnered from the cumulative effects of profound seat comfort (the massaging function was never switched off), cocooning micro climate environmental control, orchestral levels of audio entertainment and the theatre of light and vision performed by the two available screens; it is an automotive experience like no other. And the eye-tracking 3D-effect navigation set within the electronic instrumentation. No need for cinematic glasses to get the effect. The driving position itself, by the way, is also first class.

Room to stretch and grow for sure, and in every direction. But room for improvement? You betcha.

Your tester had a headache after a little while staring at that woozy 3D map. The central vents – four at the front, two in the rear – look and feel cheap, leaving us mentally redesigning them; they are frightfully out of place here; the carryover column-stalk auto lever should have been binned in 2005. And, even though the digital instruments have a number of options, none are elegant enough for the S-Class. That's an especially subjective criticism, clearly, but one that – in the context of classic Mercedes luxury sedan contenders – is justified given how timeless the Bruno Sacco era of Daimler design was. Look him up, kids.

Still, after a couple of hours behind the wheel, with our senses reset to calm, it is obvious that the S-Class cabin is a unique and wonderful place – as it should be at a cool quarter-of-a-million dollars.

Job done.

PS At 550 litres (20L more than before), the boot is massive and luxurious enough to sleep in.

You’ve bought a $400K collectible sports car capable of effortlessly deleting kilometres of highway with your family and enough luggage for a week. Usually a special edition driver's car at this price point is doing well if it has a place to put a phone and a water bottle, let alone phones and water bottles for four people - five if you really need.

Yes, in the performance car world, the Audi RS6 Avant has long been king of the convenience game and the GT holds onto that. 

The seating position and ergonomics remains comfortable, the driver’s seat being manually adjustable means it can sit even lower, there’s decent storage in the door cards, cupholders are able to be hidden, the phone charger is under the armrest, there’s a spot for small items like keys, change or glasses and the rear seats have mostly the same alongside their own individual climate controls and heated seats.

Behind those, a 548-litre boot puts most performance cars to shame, but its 1658L space when the rear seats are folded down is unbelievable for something that you’d want to take to a race circuit.

I’ve been told I’m not allowed to swear in CarsGuide reviews, so add your own expletive when I say, at $399,000, before on-road costs, the RS6 GT is expensive.

A ‘standard’ Audi RS6 Avant Performance costs $252,600, so you would really, really hope that warm feeling you get from owning one of only 22 GTs in the country is worth around $146,400. It’s very hard to imagine the physical changes to the car amount to that much money.

Of course, there’s plenty of kit in the RS6, anyway. But unique to the Avant GT is a carbon bonnet, carbon wing mirrors and carbon front fenders, a restyled spoiler, tailgate, and rear diffuser, 22-inch Audi Sport six-arm ‘Avus’-inspired alloy wheels (in white or black), RS ceramic brakes and black badging.

Inside, there are RS front bucket seats trimmed in leather, synthetic suede and carbon, contrast stitching in red, red seatbelts, black synthetic leather along the dashboard with open-pore carbon, rear window sunshades and a Bang & Olufsen 3D sound system from the 'Sensory Package' as standard.

There’s also ‘RS6 GT’ scuff plates, floor mats, puddle lighting and the individual number for each of the 660 cars on the centre console. 

There’s also manually adjustable coil-over suspension and a GT-specifically-tuned quattro sport differential.

It’s cool, but is it an extra $146K cool?

For the price, you’re almost in Ferrari territory, or you’re ticking some options boxes on your Porsche 911 Carrera T. Suppose neither of those can comfortably take a family of four on a holiday to the snow and even feel safe driving on icy roads, though.

It does happen to be about the same price as the Mercedes-AMG GT63 S 4 Door, though whether that looks as good as the RS6 is debatable.

Where are the V8s?

Right now, the only W223 you can buy is powered by an all-new 2999cc 3.0-litre in-line direct-injection six-cylinder turbo petrol engine dubbed the M256, complete with double overhead cams, an electric compressor intercooler and assistance from a 48-volt mild hybrid system and integrated starter-generator, adding 16kW and 250Nm to the 270kW of power at 6100rpm and 500Nm of torque from 1600-4500rpm.

The 9G-Tronic torque-converter automatic transmission and 4Matic all-wheel drive system combination is a first for the S-Class in Australia.

Top speed is limited to 250km/h, while the 0-100km/h sprint-time takes just 5.1 seconds in both models. Impressive for a two-tonne-plus luxury limo.

Audi’s venerable 4.0-litre, twin-turbo V8 engine remains at the heart of the RS6, though in the GT there’s no more power than the RS6 Avant Performance.

That means 463kW of power and 850Nm of torque delivered to all four wheels via an eight-speed torque converter automatic and Audi’s ‘quattro’ all-wheel drive system, making the RS6 Avant GT capable of a 3.3-second sprint to 100km/h, according to Audi. Top speed is a blistering 305km/h.

All this in a car I took to Coles.

With the aid of the mild-hybrid system, the S450 returned a combined average of an impressive 8.2 litres per 100km, which translates to 187 grams of carbon dioxide emissions per kilometre. 95 RON premium unleaded (or higher) is recommended. In the urban run it consumes 11.3L/100km (11.5 for S450L), and just 6.4L/100km (6.5 for S450L) in the extra-urban result.

At 76 litres, the fuel tank will allow a combined average range of about 927km between refills.

Do you care about this section of the review if you’ve bought one? Surely not. 

Anyway, Audi claims 11.8L/100km in terms of fuel consumption and you’d better believe it’s 98 RON minimum. 

It’s got a 72-litre fuel tank, which was depleted rather rapidly on test. While driving conditions weren’t ‘fair’ in terms of the test given the content demands of a short-term loan, there’s probably a realistic figure somewhere between the claim and the 17.9L/100km I achieved over a few days.

In former times, as the Germans say, a ‘450' on the boot indicated V8 power. In the W116 S-Class era it was one of the world's most evocative badges when ‘SEL' was also attached.

As mentioned earlier, though, it's the M256 3.0-litre turbo-petrol with a 48-volt ‘mild hybrid' electrical system that's doing the driving, to all four wheels. The real V8 W223 will probably surface later this year or in early 2022 with the S580L flagship. Bring it on.

This is not to say that S450 isn't good enough. With that electrified assistance, the blown straight six is smooth and swift off the line and rapid as the auto seamlessly steps up through all nine gears. Because it's so hushed and refined, it doesn't feel 5.1s to 100 clicks quick, but watching the speedo says otherwise – acceleration is assertive and strong right up way past the legal speed limit.

All that's missing is the burbling soundtrack of a classic Benz bent-eight. Oh well. Outstanding economy is a price we're literally willing to pay in lieu.

Even more impressive is the S450's ability to hustle along mountain roads like an overgrown sports sedan.

Now, for Australia, all S-Classes are fitted standard with an adaptive ‘Airmatic' air-suspension set-up, including air springs and self-levelling tech. In Comfort up to 60km/h, the ride height can be raised by 30mm, or lowered by 10mm under the standard 130mm baseline in Sport at any velocity, while in Sport+ it falls another 17mm.

With that in mind, yes, the standard air suspension performs a magnificent job smothering out most surface imperfections around town. Yet its real other party trick is to tighten up the chassis when corners get interesting and Sport mode is selected. Aided by progressively weighted and reassuringly responsive steering, the Mercedes tips into turns with precision and poise, slicing through with virtually no discernible body lean or understeer.

Now, we're not talking a leisurely drive on rural highways here, but Healesville's famous Chum Creek Road, where even a Porsche Cayman would feel like it's had a strenuous dynamic workout. The S-Class can be hurried along with confidence and finesse, displaying outstanding handling and roadholding for a 5.2-metre long limo. And the fact that the ride quality only suffers marginally when the red horns are out is all the more remarkable.

Back in the cut-and-thrust of inner-city peak-hour traffic, the Benz in Comfort mode continued to reveal its driver-orientated yet passenger-focused twin-personalities, zipping in and out of gaps while remaining comfy and composed inside.

Only when parking in tight spots are you truly aware that the W223 is longer than a Mazda CX-9. The optional four-wheel-steering system is claimed to slash the turning circle to A-Class hatchback levels. 10.9 metres is the claim.

The 2021 S-Class never ceases to amaze and delight.

There’s something unfortunate about how good the Audi RS6 Avant GT is from behind the wheel. That’s knowing how few people will properly get to enjoy it.

Not just because only 660 were built, but also because the majority of those 660 owners will be too worried about how much they’ve just spent on an automotive rarity to properly take it for a burn on a road, or even a track.

The RS6 was always an icon of Germany's penchant for subtle-looking cars that just happen to be capable of embarrassing much more brash vehicles, but the GT does away with the pretence and sharpens its teeth a little.

The specifically tuned rear differential makes for a more rear-biased driving experience in Dynamic mode, which means more agile cornering and a more natural balance compared to the way the RS6 sometimes feels - like a family wagon.

Its rival, the BMW M5 Touring, can go full rear-drive, but the Audi doesn’t need that as an option. It feels more capable and composed; ready to obey commands without fuss. A set of Continental SportContact 7 tyres (285/30) help there on the grip front.

The suspension underneath, adjustable coil-overs with three settings, is unique to the GT and lowers the ride height by 10 millimeters. It’s stiffer, 30 per cent at the front and 80 at the rear, and you notice it.

There’s more control and much less body roll, but the trade-off is the RS6 Avant GT is a little less comfortable on Australia’s particularly rough roads. Its 22-inch wheels don’t help.

It’s not, however, crashy or rattly. The suspension still does a fine job of stopping the driver being jostled around, but there’s a decidedly firmer response to the surface underneath. Again, still very composed.

With the new suspension, steering the GT feels easier than memory would suggest and the baseline was already good. There’s no unnecessary weight, but there’s still decent feedback from the front wheels and accuracy is bang-on.

Throttle adjustment in the corners, too, is easier with the rear differential, and it means anyone who still had reservations about Audi and understeer can be proven wrong.

The drivetrain remains unchanged from the Performance, which is a good thing. The effortless acceleration, even in the more aggressive 'Dynamic' setting with the transmission set to 'Sport' is smooth but seemingly unending.

Fortunately, the 4.0-litre V8 under the carbon bonnet sounds delightfully burbly, so getting to the speed limit or overtaking is a little treat every time. While the steering wheel paddles are there if you really need to drive in anger, the eight-speed is fine left to its own devices.

A 2.0-tonne family wagon with a V8 up front, easy communicative steering, and sporty suspension that settles well over bumps but allows enthusiastic corner attacks?

The RS6 Avant GT is in limited company.

There’s no current rating from ANCAP for the A6 in general, let alone this specific RS6, but there’s a decent suite of safety equipment and tech to keep you worry-free in the GT.

Eight airbags and more than 30 driver assistance systems from the RS6 are of course present in the GT, including adaptive cruise control, lane-keep and warning, emergency brake assist and cross-traffic alert.

Audi’s also got surround view cameras for parking, which also includes warnings for approaching vehicles or objects, plus there are preemptive measures the car can take in an impact like tightening the seatbelts or braking to avoid a second collision.

The second row also has three top tethers and ISOFIX anchor points on the outboard seats for mounting child seats. 

Unlike many luxury brands that persist with a sub-par three-year warranty, Mercedes-Benz offers a five-year/unlimited kilometre warranty.

Intervals are every year or 25,000km, with a capped price service plan starting at $800 for the first year, $1200 for the second year and $1400 for the third year, totalling $3400. Alternatively, there is a Service Plan starting at $2700 for the first three years (saving $700 from the normal capped-price service plan), $3600 for four years and $5400 for five years.

Audi’s five-year/unlimited kilometre warranty is below industry par, though most premium brands are in the same boat.

Twelve years of bodywork warranty against corrosion is also included, as is a five-year run of free Audi roadside assistance.

Five-year service plans can be purchased, or customers can buy back-to-back two-year extensions for the warranty, servicing and roadside assistance.