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Mercedes-AMG C43 Coupe vs Audi S5 Coupe vs Infiniti Q60 S Sport 3.0t (2017) review

Published: 20 March 2017

► Three-way sports coupe shoot-out
► Merc C43 vs Audi S5 vs Infiniti Q60
► But which coupe is sharpest of all?

In this somewhat back-to-front world in which we live, the cost of less is sometimes more. More legroom on that long-haul flight? That will be extra, sir. Two fewer doors and less rear legroom than the saloon? That will be extra, sir.

And so it is that, as a general rule, you must lose the space, versatility and value of a saloon if you want the greater style and cachet of a coupe. Whether it’s a worthy trade or not is entirely your call, but clearly there’s something in it – otherwise Infiniti wouldn’t go to the trouble of creating a Q60 from the bones of the Q50.

Still in relative infancy in the UK, Infiniti is finally getting the models to mount a more concerted challenge to the established German hierarchy. The recent QX50 concept was a demonstration of a more cohesive design approach, while the Q60 is a production-reality step forward for the brand. 

Infiniti Q60

Based on the FM platform that also underpins the closely related Q50 saloon, the Q60 arrived in the autumn of 2016 with an all-petrol line-up; a 2.0-litre four-cylinder turbo offering 208bhp and a more exotic 3.0-litre V6 twin-turbo dishing out a hefty 400bhp. Available solely with a seven-speed automatic transmission on all engines and four-wheel drive only for the V6, the Q60 3.0t starts at £42,990.

Audi S5: a gateway drug to RS4

Inevitably there is an Audi designed specifically to occupy this place in the market, and on this occasion it is the role of the newly introduced S5 to act as a counterpoint. Like the Infiniti, the regular A5 coupe is spun off a lower-numbered saloon with significant changes to the bodywork.

In S5 guise it gets a new 3.0-litre turbocharged unit, ditching the old supercharged version and siting the blower in between the cylinder banks for maximum response. With 349bhp, quattro all-wheel drive and an eight-speed Tiptronic transmission as standard, performance is promising; the S5 coupe starts at £47,000.

Completing the trio is the Mercedes-Benz C-Class, tested here in AMG C43 4Matic form. Although the basic car is older than the other two it was last summer that Mercedes introduced the halfway-haus between the most powerful regular models and the 4.0-litre V8 C63 AMG. With a twin-turbocharged 3.0-litre V6 spinning away up front and sending 362bhp to all four wheels (with a rear bias), it is no surprise that the Merc is very closely matched to the Audi. In this guise the C43 AMG starts at £47,605.

Design details

More of a surprise is how each car ploughs its own particular furrow when it comes to the exterior design. The Q60 is a car still in search of a complete identity; the wide family grille is a genetic trait it could do without, and some of the details are hit and miss. The sliced-off rear side window looks a little contrived and if you stand side-on and block the A-pillar rearwards with your thumb the front end looks almost indistinguishable from a BMW 4-series. That said the overall shape is a success, with a strong shoulder line, a tidy rear and good stance on standard 19-inch wheels. It has enough of its own personality to be appealing to buyers.

It also makes the S5 look a little plain. Discreet but taut must be writ large on the design studios of Ingolstadt, for the Audi follows this mantra to the letter. Conservative Daytona Grey paint does it no favours and the 19-inch wheels contrive to look a little small, even if the basic A5 shape, with its gentle curves and flared hips, is improved over the outgoing car. It almost feels like the S model is holding too much back visually in preparation for the RS5 to muscle its way in.

Mercedes-AMG C43 Coupe

In its own way the Mercedes-AMG is just as predictable, being firmly tied in with its saloon and estate siblings as well as the rest of the Mercedes range. But there’s nothing wrong with that when the proportions are this good; the minuscule front overhang, sweeping flanks and pert tail give a hint of muscle car, although the optional 19-inch wheels are a near-essential (and relatively inexpensive) £595 upgrade. Some may find it a touch brash compared to the whispering discretion of the Audi, but as a piece of sculpture sat on your driveway it’s most likely that the Mercedes will have you pulling back the curtains for a furtive second look.

Time to hit the road...

Our route kicks off with middling, out-of-town A-roads, the Infiniti leading the pack. At a cruise the Q60 is restfully undemanding, with the six-cylinder unit happy to thrum in near-silence and the ride on the right side of firm for such conditions. The cabin is more of a stress at times, though, with the twin-touchscreen set-up all too jarringly feeling like two different decades colliding in the same dash.

Material quality is strong, however, with the cheaper plastics sufficiently squirrelled away, and plenty of leather and matte chrome tastefully applied elsewhere. There’s plenty of scope for tweaking the driving position too, and the seats are generous in their support. Those travelling in the front will have no complaints in terms of space.

Should you be able to get adults in the rear, however, expect grumbles; leg- and elbow-room are narrowly the best here, but the headroom is simply inadequate. Save the back seats for kids or adults with persistently poor  posture.

Inside the Mercedes-AMG C43 4Matic

There’s better balance in the Mercedes between style, practicality and space. At first the cabin feels a little more enclosed than the Infiniti, but put that down to a tighter window line and more enveloping dash. Familiar it may be but the C43’s cabin feels the most special here, even allowing for the decently priced brown leather trim at £750.

Mercedes-AMG C43 cabin

The infotainment screen looks a little ungainly plonked on the top of the dash, though admittedly it’s been plonked in an ergonomically sound position, while the minor controls are well placed and easy to operate once you’re familiar with the operation of the wheel and touchpad. With the boring functionality taken care of, the quality of the design and the materials is a welcome boost; climbing aboard feels more of an event than in the other two.

Audi S5 cabin

That’s essentially the only criticism that can be levelled at the S5. Its cabin, lifted from the A4, is a masterpiece in efficient and smart design. There’s a reassuring snap and click to all of the controls, the optional Virtual Cockpit teams well with the central screen and HMI interface, and it rarely takes more than a couple of seconds to get what you need – the possible exception being the occasionally high standards of calligraphy demanded by the touchpad. But it’s a bit sterile in here, particularly in comparison with the Mercedes, and while the quality is more than good enough for the price, a bit more of a feelgood factor wouldn’t go amiss either. 

All three cars offer a spectrum of modes and configuration options to suit the driving conditions, with equally varying degrees of efficacy. In the Infiniti the drive mode selector covers everything from Snow to Sport, with a personal mode allowing mashed-up selections of engine and transmission, with further sub-divisions for the adaptive steering.

The original steer-by-wire system, first introduced on the Q50, proved to be as appealing as it sounded; this second-generation system is better, but still ranks behind electric and hydraulic steering for the ultimate in feel.

Audi vs Mercedes vs Infiniti

What it does do very well is allow you to relax as it filters out the ceaseless road imperfections that can become tiresome on a long journey, the downside being it’s many of those same messages that you actually desire when the going gets interesting. Overall the Q60 delivers a high level of competence but not a great deal else; there’s traction, grip and a reasonable degree of balance but the satisfaction comes from keeping things tidy rather than really moving the car around. For some this will be perfectly acceptable, but its rivals offer more.

On the road in the C43

Switch to the Mercedes and although it wears the AMG tag, it does without the Race mode you’ll find on Affalterbach’s finest. Instead you get Sport+ as the spikiest of the drive programmes with further tweaking of the gearbox operation also available. What the C43 does best is cover a variety of roles with equal aplomb; Comfort lives up to its billing, slackening off throttle response and smoothing the ride and gearbox actions to make ordinary driving effectively as relaxing as the standard car.

Turn everything up as high as it will go – it’s rare you’ll want intermediate modes – and there’s an all-round tautening of its behaviour without becoming unmanageable. The steering isn’t flawless, with a centre dead-spot that’s larger than ideal, but once a few degrees in it offers satisfying levels of accuracy and feel, and is the best of the trio.

That translates into the most engaging drive here; the 4Matic system is split with a rear bias (31:69) so there’s some adjustability available, and it shows keenness by seeming to shrink around you as you start to press on. It’s certainly worthy of the AMG tag in this respect.

Audi S5 at the limit

An early adopter of multi-modal offerings with its Drive Select system, the Audi’s selection is the most comprehensive here, especially if your specification choices include the sport differential and adaptive steering. Comfort and Efficient mode don’t affect the way the S5 drives significantly, but in Dynamic mode there’s a clear increase in noise from the exhaust, sharper throttle response and greater weight to the steering.

Audi S5: settings overload

In fact it is the steering, with the Dynamic Steering option boxed ticked on this particular car, that has a significant influence on how the S5 feels to drive. There’s no questioning its responses are sharp, particularly with the Drive Select in Dynamic mode, and there’s weight to its operation rather the wheel spinning easily in your hand. Yet there’s still a level of disconnection you just don’t get with a more conventional set-up; occasionally you can turn in so quickly that it feels like it takes the rest of the car a fraction of a second to catch up.

Sharpness of response is only part of the recipe for fine steering. That reflects the whole driving experience, which is lower-level quattro to a tee; efficient, capable, quick and undemanding of the driver – but ultimately a little cold. With the sport differential fitted there’s a little more scope for making the S5 dance if you want to, but it requires a level of commitment you’re unlikely to provide if you’ve shelled out £47k of your own money. It’s the car for rapid travel in all weathers, just not necessarily the longest way home.

Performance, engine specs

Where the established order of things is a little upset is on the performance front. It’s no coincidence that these rival coupes have such a remarkably similar layout: twin-turbocharged 3.0-litre V6s with four-wheel drive delivering power through an auto-only gearbox.

The Infiniti is the joker in the pack here, crashing the party long-established by the other two and instantly impressing with its responses, engagement and even the noise. Like the other two it’s impressively quiet and smooth when holding a steady cruise but very little encouragement is needed via the throttle to wake the beast within.

Audi S5

Its 400bhp means it’s 38bhp up on the Mercedes-AMG and 51bhp ahead of the Audi, and while its conventional automatic can’t shift as quickly as the other two the fact that it dishes out its 350lb ft of torque from just 1600rpm makes it an effortless sprinter, and one that feels always ready to play.

Acceleration, 0-62mph times

That the Q60 isn’t the quickest car here is something of a surprise; 0-62mph in 5.0 seconds flat is undeniably fast, but in this company a kerb weight of 1892kg is relatively portly, and that mass blunts performance as surely as chips follow session.

Despite the lowest power output here the S5 rattles off the 0-62mph measure in 4.7 seconds, no doubt helped by the slickness of the Tiptronic transmission – which feels no slower than a dual-clutch ’box on the way up at least – and the lowest weight, with a substantial amount of aluminium in its construction.

The new V6 motor is deliciously responsive even in the most dormant of drive modes, with torque seemingly on tap instantly and, like all the best performance cars, it is rare that you need to use all the power available; sometimes you just do it for fun. The six-cylinder motor has plenty to say for itself too, with a vocal rasp available in varying volumes depending on how the car has been configured, although it is a curiously rear-biased sound, with all of it appearing to come from just below the rear seats. 

Which coupe is your favourite?

That strange effect is all the more noticeable after a blat in the C43. It fires with a notable blare even in the most conservative mode, although it is in no way excessive. But release the hounds a little by switching mode and this engine feels very much like a son of the 4.0-litre bi-turbo V8 in the C63; sharp, vocal in a genuine sense rather than enhanced by Auto-Tune, and ready to play.

It has the most torque here, with 384lb ft arriving at 2000rpm, and being almost 160kg lighter than the Infiniti means it can match the Audi in the race to 62mph. The transmission is sufficiently sharp whoever takes charge of the shifting, and with plenty of traction it is usable performance as often as possible. Pleasingly, this also feels like genuine AMG hardware.

Verdict

Given how laughably closely these cars are matched on the spec sheet it shouldn’t come as a surprise that they finish closely on the podium too. Nor perhaps that the unfavoured Infiniti should come third, but it is a highly credible third; it is deliciously fast thanks to that cracking new engine, offers a highly competent drive and from most angles at least is a good-looking machine. But it lacks a little edge, both in its driving experience and character. Competence is the minimum requirement at this level.

The S5 takes competence to an entirely new level. Each improvement over the outgoing car is tangible and worthwhile, from the latest generation tech and the ultra-slick cabin to the new six-cylinder turbo engine; it’s even the most efficient machine here, should such things matter to you. It is a car you can buy with unwavering confidence that you’re doing the right thing and won’t be disappointed, such is its all-season and all-circumstances capability.

Unless you’ve driven the C43, that is. The S5 runs it close if you go by the cold reason of the tape measure, but if you’re about to spend £50,000 on something less practical than a saloon we think you’re entitled to a bit of fireworks. It has more fire in its belly than the other two put together, and while it will always be little brother to the C63, it is clearly the work of AMG. Fast, engaging, fun, comfortable and with a distinct sense of style inside and out, it is the car you should choose if you want something with soul. 

More comparison tests by CAR magazine

Mercedes-AMG C43 vs Audi S5 vs Infiniti Q60

Key Tech: Audi S5 Driver Assistance

Adding the Tour Driver Assistance Pack brings a host of tech to the S5 including adaptive cruise and traffic jam assist, which controls acceleration, braking and a degree of steering assistance below 40mph. Once you learn to trust the system it works well up to a point, and takes the headache out of stop-start motorway traffic, but it can feel like the steering is ‘bouncing’ within the lane, over-correcting one way and then the other – pretty much the opposite of stress-free… 

Merc-AMG C43 4Matic

Key Tech: Mercedes 4Matic all-wheel drive 

The four-wheel-drive system employed by the C43 isn’t the same as the 4Matic+ layout used by the beastly E63 AMG, so there’s no variable split front to rear and no option to switch it out for rear-drive mischief. It is, however, fixed with a 31:69 bias front/rear, allowing a degree of rear slip in the right conditions and with the ESP set to either Sport mode or switched off. 

Key Tech: Infiniti Adaptive helm

The Directive Adaptive Steering system fitted to the Q60 is a second-generation version, following criticism of the original set-up. But it remains the only drive-by-wire arrangement available on the market. On this version of the Q60 there are six modes for the steering alone, with the Sport+ mode and Dynamic+ response level selected to access the sportiest set-up. It delivers very sharp responses in the most aggressive mode, although always with next to no feel, which takes acclimatisation. Try before you buy.

By Matt Joy

CAR magazine’s associate editor

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