Audi A7 TDI Biturbo Quattro v Mercedes-Benz CLS 500 : Comparison Review

Wholesale revamps in large premium ‘coupe limousine’ circles have been thin on the ground of late. However, segment leaders the Audi A7 Sportback and Mercedes-Benz CLS have recently received refreshed exterior styling together with revised equipment levels, pricing and some mechanical specifications.

For a long time, Mercedes-Benz, which debuted its CLS range in Australia back in 2004, virtually owned the jumbo-sized coupe segment that defies definition by way of seat or door count. It would be six years before Porsche lobbed its Panamera into the mega-luxury, swoopy-roofed fray on local turf, and a further two years until Audi's A7 and BMW’s 6 Series Gran Coupe followed similarly stylish suit.

Facelifted in February with the rest of the CLS range, our CLS 500 test car sits below only the maniacal CLS 63 AMG S as the supreme luxury variant. At $169,900 plus on-road, the considerable price tag affords commanding prowess under foot, its 4.7-litre bi-turbo V8 sending 300kW and 600Nm to the rear wheels by way of a new nine-speed automatic transmission.

Now, some may think the similarly twin-turbo V8 Audi S7 Sportback as the most logical competitor. However, despite the similar $179,900 ask, the S7 is arguably sportier in pretensions, which leaves the 3.0 TDI Biturbo quattro version as the A7 Sportback leveraging indulgent luxuries while underpinned with effortless and inconspicuous potency.

The A7 Sportback Biturbo, though, plies its talents with a markedly different powertrain: a 3.0-litre bi-turbo V6 diesel via quattro all-wheel drive. And while the ‘high-power’ TDI engine offers a mere 235kW peak – a 65kW deficit to the CLS 500 – the Audi offers an extra 50Nm of torque (650Nm total) plied through all four wheels, which levels the playing field significantly.

At $144,900 plus on-roads, the Audi has a far more attractive base list price. However, you will need to tick a lot of option boxes to match the level of equipment loaded into the Merc.

The CLS500’s extensive features include heated and ventilated seats, adaptive cruise control, digital radio and TV, and a 360-degree around-view camera system. You can add niceties such as a Bang and Olufsen sound system to the Audi, though it is still missing standard-bearing luxury items such as an electric steering column and seat heating.

That said, the A7’s interior is a cut above Audi’s usual high-class form. The materials feel premium to the touch, the design is elegantly clean and well laid out and the MMI infotainment system has been updated with better graphics and combines with the digital instrument cluster to display everything from speed to mapping.

On the outside, the A7 incorporates the sharpened facelift that debuted locally in March, including the distinct ‘single-frame’ front grille and new ($2500 optional) Matrix LED lighting.

The CLS facelift integrates exterior restyling aligned with other recent Benz updates such as the CLA and C-Class. It has its own new, deep and bejewelled grille design and new standard-fitment Multibeam LED headlamps also.

Unfortunately, the CLS’s interior update missed out on scoring the excellent S-Class derived buttons and switchgear that trickled down into the C-Class and other recent models. It is, however, easy to use and full of premium touches, though the foot park brake and finicky telephone-like buttons do feel a bit yesteryear.

What the CLS interior did get is a new, high-resolution 8.4-inch floating display. Like Audi’s MMI interface, Mercedes’ COMAND system controls everything from the console. It isn’t quite as intuitive as MMI, though it’s easy enough when you get the hang of it.

Though the coupe limousine format aims to provide supreme four-adult comfort, both the Audi and Merc present concessions in rear cabin space. Those alluring rooflines compromise rear headroom, the slightly roomier Mercedes being a little more accommodating for taller passengers. Rear legroom in both coupes is acceptable rather than generous. That the A7’s rear windows only open halfway is more an annoyance than anything like a deal-breaker.

The Mercedes is strictly a two-plus-two seating configuration, handing the Audi, with its five-seat flexibility, the advantage in the convenience stakes. The Sportback’s liftback design also allows easy access to the luggage area that converts from 535 litres to a whopping 1390 litres with its 60:40 split rear back rest down. The CLS’s conventional boot does allow a generous 520-litre capacity, though without foldable rear seat utility.

On the move, the CLS 500 is suitably serene in character, its V8 remaining quiet and refined around town one minute, offering effortless progress on the open road the next. Push on and there’s a faint rumble accompanied by a surge in low-end torque that’s both urgent and satisfying, though that smooth and tempered character never becomes uncouth or unruly.

To come close to achieving Merc’s claimed 8.6L/100km combined consumption, though, you’ll need to engage the Eco drive mode and treat the throttle pedal very sedately indeed. The union of engine and the newly introduced nine-speed automatic is strong, though the fuel saving benefits of its tallest ratio are largely redundant outside of high-speed German autobahn cruising.

No matter what the road speed, the CLS 500’s adaptive Airmatic air suspension provides a plush and polished ride. And its default Comfort mode has enough body control and surefootedness at a brisk clip that there’s really little need to engage the firmer Sport setting in situations beyond the twistiest of back roads.

For daily commuting duties, though, the Audi is marginally more comfortable in ride quality, with the optional air suspension on our car offsetting any compromise of the fitted low-profile rubber. Not only does the A7 combat sharp-edge road inconsistencies better, the cabin has finer shock and noise isolation from the elements and the cabin space is a more tranquil place to be on the move.

Further, the A7’s silken eight-speed transmission is a touch more refined and a little more intuitive while self-shifting than the CLS 500’s nine speed. And match to the broad torque wave afforded by the 3.0 diesel, it seems almost impossible to catch the powertrain off the boil.

Where diesel trumps petrol by a significant margin is in fuel consumption, the Audi claiming a frugal 6.1L/100km figure – frankly astonishing for around two tonnes of luxury-laden car that certainly isn’t left wanting for rapid forward progress.

To properly stretch their legs, we took the German duo off street to the RAC DTEC (driver training) facility, near Perth Airport.

While rain hampered fully exercising the CLS 500’s rapid 4.8-second 0-100km/h prowess, there’s certainly a satisfyingly tough character lurking within which surfaces once Sport drive mode is engaged. It never becomes a snarling, fire-breathing animal like its CLS 63 AMG kin, but the 4.7-litre engine does growl let off its chain and pops and crackles nicely on the overrun.

It was here the CLS really came into its own, with its RWD V8 configuration catering to the inner revhead in us (even if the revhead buying a CLS may be dressed like a banker). Though its engine isn’t the snarling hell-beast found in the CLS 63 AMG, Mercedes knows how to make great V8s and the CLS 500’s unit is a ripper. The cabin’s never drenched in ear-bleeding sound, but the 4.7-litre still elicits a raucous growl with the requisite snap, crackle and pop when the pedal’s floored.

That nine-speed, too, really comes to sharpened life in Sport, rapid in its changes and holding on to ratios nicely.

While 50Nm short of the diesel Audi, the V8’s still formidable 600Nm, from just 1600rpm, is ample energy to make for a properly exciting punt. It feels more comfortably at home being pushed than the A7. There are even some neat hidden performance touches, such as the active seat bolsters that hug you during high-speed cornering.

That said, the A7’s 3.0-litre Biturbo – the ‘high-performance’ diesel – is amazing. There’s none of that traditional diesel ‘rattle’, it’s smooth throughout the rev range, pulls hard right to its redline and has the sort of throttle linearity few other diesels can match. And it sounds amazing: a V8-like rasp but with completely unique and compelling timbre.

The A7 takes 0.4 seconds longer than its Mercedes rival to hit the 100km/h from a standstill, and quattro all-wheel-driven grip makes a mockery of the wet conditions.

Annoying, though, is how little changing its drive modes affects the Audi’s character, and how the transmission belligerently upchanges autonomously well before the engine’s redline in fully manual mode.

For large and heavy cars, each is remarkably nimble with relatively minimal body roll and firm body control when driving enthusiastically. The sheer force and tireless consistency of each car’s powerful brake package is also truly impressive.

So which coupe limousine best deserves pride of place in your driveway? The choice should really be one of personal preference rather than a judgement on balance of merit.

The Audi is the smoothest operator, slightly more practical in functionality and certainly more affordable at the fuel station. The Merc, meanwhile, offers slightly more driver-focused character, has more standard gear and is arguably better looking externally.

Either bet is a winner. The ideal choice, then, is which winning message you want to send to the world.

This story originally appeared on Photography and video by Mitchell Oke.

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