Is the subtle stealth of Audi’s S6 or the GT53’s showmanship the key to finding the perfect performance-comfort balance, that holy grail of motoring?

The adage, there’s more than one way to skin a cat, may elicit a chorus of howls from animal lovers, but sage folks know that said feline is perfectly safe. It serves only as an analogy that the means to a common end needn’t necessarily follow the same path.

Putting pets aside, for now, it’s also an apt adage when looking at Audi’s S6 and the Mercedes-AMG GT53 4-Door Coupé. While the yawning price gap precludes a direct comparison, there are enough quantifiable parallels at play to warrant a side-by-side look. Both sport four doors and six-cylinder engines coupled to all-wheel drivetrains. They also sit in the same brackets of their respective model lines, all of which is aimed at serving up sophisticated motoring and a healthy dose of excitement in equal measure.  

But it’s the divergent paths these cars take towards their goal that makes things interesting. Will the S6’s soft, stealthy approach wither in the face of a GT53 that rips its tie off and spoils for a fight, or is subtlety the key to carrying off this balancing act?

What are they?

There is a certain uneasiness to labelling these premium cars inbetweeners but it’s essentially what they are: bridges between the upper reaches of their standard model lines and their proverbials-to-the-plasterwork V8 halo performance cars.

In the S6’s case, Audi has basically taken an A6 Sedan and given it a sneaky shot of steroids; subtly beefed up the bodywork; tightened the chassis; and slipped the company’s 2,9-litre twin-turbo V6 petrol engine into its nose. It’s created a 331 kW AWD sleeper which serves as an appetiser to the 441 kW V8-engined RS6. Quite a straightforward arrangement, right?

Well, it’s certainly easier to place than the GT53. In a product line-up dwarfing its Ingolstadt rival, Mercedes goes to great ends to ensure there’s an AMG-flavoured offering at every turn, be it in any number of four-, six- or eight-cylinder permutations.

The GT53 has been posted as a package that combines the AMG GT’s performance credentials and sporty looks with a spot of four-door practicality ... provisos oddly met by at least two models from the company’s C- and E-Class lines and closer still by the eye-catching CLS53; all of which share their MRA platform – and some of their 336 kW 3,0-litre inline-six turbopetrol engine  – with the GT53.

Styling

When it comes to aesthetics, the S6 and GT53 are as far removed from one another as possible within this bracket.

As is often the case with Audi’s performance-oriented models, the treatments doled out to the S6 are an exercise in subtle purposefulness. A massage of front and rear valances here, standard HD Matrix LED headlamps, the mildest smattering of S badges there and a quartet of sizeable exhaust tips are the only suggestions this Audi has a little something up its sleeve. Our test unit rolled on a fetching set of optional (R21 400) 21-inch rims but that was about the only marked concession to its otherwise well-concealed performance credentials. It’s an approach that lends it a stealthy Q-car quality that will appeal to those wishing to fly beneath the radar but it may prove a little too veiled for some.

Cue the GT53 and the S6 all but dissolves into the background, partly because of the amount of tarmac its frame occupies, but mainly as a result of its AMG GT-inspired styling. Smoothing the high-performance AMG GT’s skin over a hulking four-door coupé canvas was never going to be easy. With a profile incorporating the two-door’s long bonnet and a roofline that arcs into a bobbed tail, replete with striking slivers of brakelamp and that gaping Panamericana grille, it elicits plenty of attention.

Interiors

The GT53’s bold aesthetic treatment continues into the cabin and is a hit-and-miss in overall execution. There’s definitely visual drama in the substantial slab of centre console and the facia with illuminated seams, eyeball air vents and vast MBUX infotainment/instrument panel; however, beneath the skin, things go awry.

The quality of Mercedes’ interiors has drawn a good deal of criticism in recent years, with substandard plastics and creaky fixtures making an unwelcome appearance in some but not all models. Unfortunately, the GT53’s cabin feels disappointingly low-rent in places for a car wearing a R2-million price tag.

It contrasts starkly with the S6’s innards which, like the exterior, is an exercise in classy understatement and is solidly constructed from materials with a decidedly more premium feel. Admittedly, the adoption of digital panels with haptic feedback for the ancillary controls didn’t draw unanimous praise. They are fiddly to use on the move and a veritable fingerprint magnet but in terms of perceived quality, it does feel as though your R1,4-million has been well spent.

Adopting a four-door coupé form often compromises interior packaging but the GT53’s cabin isn’t that much smaller than that of the spacious S6, with only the narrow glasshouse and deep doors sapping some of that visual spaciousness. Ultimately, it’s the S6’s more conventional three-box design that proves most practical, incorporating a cavernous 400-litre boot that expands to 984 litres with the rear seats folded versus the GT53’s more modest 336-litre luggage bay.

Powerplants

Cylinder configuration aside, there’s little to separate the two. Both mount six-cylinder engines with 48 V mild-hybrid systems coupled to all-wheel drivetrains. The GT53’s EQ Boost and S6’s MHEV systems are also very similar and serve to spool up their respective turbochargers to 70 000 r/min in a bid to eliminate turbo lag. A task at which they are impressively effective; a jab of the accelerator in either car is met with sharp power uptake at any speed.

In addition to the standard eco/comfort/sport presets, both cars’ drivetrain-management systems enable you to tailor such parameters as throttle response, steering, suspension, shift patterns and exhaust soundtrack to individual preference.

In keeping with their characters, the two powerplants present quite differently. The S6’s 2,9-litre V6 unit ably conceals its 331 kW and 600 N.m of torque under a low-key soundtrack that gives way to the odd whumph from the tailpipes only when provoked and hooked up to the drivetrain-management system’s most aggressive setting.

Although it’s quite softly spoken, the S6’s powerplant is by no means meek. Despite posting a marginally slower 0-100 km/h sprint time than the GT53, a look at their respective in-gear acceleration figures sees the Audi whipping through those 20 km/h increments quicker than the Mercedes. It’s an impressively flexible unit that never seems to fall out of the powerband, regardless of how much you manipulate the quickfire paddle shifter on that wonderfully smooth and responsive eight-speed transmission.

We were very taken with Mercedes-AMG’s 3,0-litre inline-six unit when we first sampled it in the CLS53 and our sentiments remain unaltered with its application in the GT53. It has a real Jekyll and Hyde demeanour, showing typical straight-cylinder silkiness when cruising and baring its teeth once a more aggressive stance is taken. Our test unit’s optional sports-exhaust system really brought out the GT53’s animalistic side, leaving a chorus of thumps, huffs and the occasional rifle-crack backfire in its wake.

The unit melds well with the nine-speed ‘box, managing smooth, languid shifts in more comfort/eco-friendly settings through to a redline-hugging, flash between ratios that allows you to extract every ounce of the 336 kW and 520 N.m on tap when tackling a twisty road in sportier drivetrain presets.

Both units are deeply impressive but it’s the Audi’s engine that strikes a better balance between ballistically fast transit and refinement than the GT53, which doesn’t settle down quite as much when easing off the pace.

Given their genteel-express provisos of combining long-distance comfort with plenty of B-road-tackling entertainment, it’s interesting how they balance those respective traits.

The balance

On the comfort-performance spectrum, the S6’s execution is on the softer side. While both feel sufficiently planted at motorway speeds, driving the Mercedes-Benz is less serene. Our test unit exhibited an unwelcome spot of wind whistle from the A-pillar glazing and a fair bit of tyre roar permeated the cabin.

By contrast, the S6’s ability to isolate you from motorway noise makes it feel as though you’re hermetically sealed into its cabin. From seats that are comfier than the form-hugging items in the GT53 to its more relaxed steering and a granite-hewn interior, the S6 simply acquits itself civilly on the long road.    

Neither car’s ride can be described as plush but the S6 is noticeably more composed. Both test units were fitted with optional adaptive air suspension setups (R16 490 for the Audi; R33 300 for the Benz) stiff enough to set less gym-toned bits of their occupants jiggling over closely spaced road imperfections. Despite its larger alloys being more aggressively shod in 35-profile rubber, the S6 better weathers the majority of driving scenarios than the GT53 and its 45-profile 19-inch footwear. Perhaps it’s exacerbated by the creaky interior trim but the GT53 simply doesn’t have the Ingolstadt car’s finesse and isn’t as adept at quickly recovering from jolts over broken surfaces.

Once speeds pick up and the corners grow tighter, the GT53 shrugs off its round-town clumsiness. The lumpiness is ironed out and the steering – which was a touch too finicky in more sedate driving scenarios – has accuracy and responsiveness that ever so slightly bests the S6’s marginally slower rack.

As in the Audi, you can’t feel the rear-biased AWD system apportioning torque between the axles, but you can appreciate the massive reserves of grip it serves up. Factor in the taut chassis’ ability to rein in that heavy body under fast directional changes and the GT53 does an impressive job of smoothing itself around its pilot when tackling roads with the sort of vigour you’d otherwise question in a car this large.

Does this leave the Audi cold by comparison? Absolutely not. Its steering may not have quite the GT53’s alertness, yet, there’s still plenty of weight and feel and its combination of fluid body control and limpet grip make it a thoroughly engaging drive. Like the GT53, the S6 we tested was fitted with an optional rear-wheel steering system (R29 800 and R28 770, respectively) that turns the rear wheels a couple of degrees when cornering at speed. In both cases, it goes hand in hand with lateral torque vectoring to do an impressive job of countering understeer, tucking the car’s nose into corners in a manner that’s fluid and precise.

Serious braking systems featuring sizable 300 mm-plus discs all round do a remarkable job of scrubbing off speed; both cars garnered an “excellent” ranking in our standardised 100-0 km/h braking tests. The Audi’s system, in particular, was ruthlessly adept at bringing the two-tonne sedan to a halt, doing so in a face-distorting 2,64 seconds. To put that into context, that’s only a 10th of a second off the Porsche 911 Carrera S’ average. Some of us did, however, find the Audi’s pedal modulation a bit sensitive and the brakes felt grabby at times.  



TEST SUMMARY

Trying to bake an equal measure of comfort and seat-of-the-pants driving excitement into a two-tonne sedan can be likened to furiously thrashing out a Metallica guitar riff on a Stradivarius: it can be done but the result will likely be less of a musical masterpiece and more of a mess of snapped strings and splintered woodwork. If there was ever a car to come incredibly close to pulling off this difficult feat, it’s the S6.

While the GT53 is marginally more engaging towards the edge of the driving envelope, it hardly eclipses the S6 and does so at the cost of the Audi’s element of everyday comfort and refinement that makes it such a deeply satisfying car to drive.

As we said at the beginning of this test, there are factors which preclude a direct comparison and some may argue that the GT53’s spiritual relationship to the AMG GT could account for its less civilised demeanour; but the S6’s ability to serve up nine-tenths of the GT53’s driving prowess, its superior build quality and a far more generous list of standard features at a price point that’s more palatable than the GT53’s R2-million only serve to cement its position as a brilliant all-rounder.  

ROAD TEST SCORE

GT Mercedes-AMG GT53 4Matic+ 4-Door Coupe
  • Price: R2,280,680
  • 0-100 km/h: 4.5
  • Power ([email protected]/min): 320 KW @ 6100
  • Torque ([email protected]/min): 520 N.m @ 1800-5800
  • Top speed: 285
  • Claimed cons. (l/100 km): 9.4 l/100 KM's
  • C02 emissions (g/km): 215 g/KM
S6 Audi S6 TFSI quattro
  • Price: R1,401,500
  • 0-100 km/h: 4.5
  • Power ([email protected]/min): 331 KW @ 5700-6700
  • Torque ([email protected]/min): 600 N.m @ 1900-5700
  • Top speed: 250
  • Claimed cons. (l/100 km): 8.3 l/100 KM's
  • C02 emissions (g/km): 193 g/KM