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Audi RS5 vs BMW M4 vs Mercedes-AMG C63 comparison

By Andy Enright, 29 Oct 2018 Comparisons

Audi RS5 vs BMW M4 vs Mercedes-AMG C63 comparison

Audi lobs a 331kW grenade into the ubercoupe sector in the chiselled form of its latest RS5. Should BMW and Mercedes-AMG be worried?

AUDI can’t build a sports car. Everybody knows that. Everyone apart from the engineers who built the revolutionary ur-Quattro, the borderline genius B7 RS4, the disruptive R8 coupe and the astonishing R10 TDI racer – a diesel that dominated at Le Mans even when Ingolstadt voluntarily used the same engines in the 24-hour race as it used in practice and qualifying.

So it ought to be obvious that there’s a pool of hugely talented chassis and powertrain people at Audi. What’s truly frustrating is that this rich vein of dynamic know-how has all too often been neutered by the might of marketing and design, the power of the brand going rogue and often bringing us some strangely compromised road cars.

The premise of this test, therefore, is to discover whether the latest RS5 comes from the ‘good Audi’ that brought us those aforementioned gems or the other bunch, the crew who gave us the 2010 RS5 V8, a true collector’s piece for the connoisseur of plough-on understeer. Even if it’s from the former camp, it’ll have its work cut out against the BMW M4 Pure and the Mercedes-AMG C63 S Coupe. The M4 doesn’t brook too many surprises, the M3 Coupe/M4 bloodline representing a durable class benchmark.

Read next: 2018 Aston Martin Vantage vs Porsche 911 Carrera 4 GTS vs Mercedes-AMG GT C performance comparison review

 

The Pure trim is an Australia-only model that strips out big-ticket items like adaptive LED lights, leather and premium audio system. Mechanically, it only differs from the M4 Competition by switching from 20- to 19-inch alloys. The Pure shares the Competition’s 331kW/550Nm 3.0-litre twin-turbo six and has an identical suspension tune, though our test car featured the 20s optioned back in (for $2500 more). With a $139,000 base price, the M4 Pure is comfortably the most affordable car here.

The AMG has clearly been on the juice, now sporting muscular wheelarch bulges, fat rubber and an aggression that’s entirely absent from its comparatively snake-hipped C43 sibling. The pugnacious stance works well, this remedial work fixing the standard coupe’s rather apologetic rear end. The only V8 of the trio, the 375kW/700Nm 4.0-litre Merc fronts up with the most grunt and the heftiest sticker price of $163,612. Add $9900 to that to get the car as tested here, complete with AMG ceramic front stoppers.

Slotting neatly between these two bookends comes the 331kW/600Nm 2.9-litre V6 Audi RS5 which has been sensibly pitched at $156,600. The eye-catching Sonoma green paintwork, an extended carbon package (including the roof and engine cover) and a Technik package, which includes colour head-up display, Matrix LED lights and a Qi wireless charger, bumps that up to $179,346 as-tested.

FIRING UP more than 1000kW of aggro at 6am is going to make you unpopular, even in a town as octane-addled as Bathurst. The Merc’s bent-eight emits exactly the correct frequency to turn motel windows into giant drum skins, bleary-eyed curtain twitchers unable to figure out at which miscreant to direct their stink eye. It’s a fat, meaty wub-wub with an old-school appeal that sounds anything but turbo-neutered. The M4 is the midrange, with the RS5 adding some tinnitus treble to really round out the sonic barrage.

Received wisdom has it that the C63 S is going to be cast as the hooligan here, the point-and-squirt hot rod that’s long on drama but light on subtlety. It plays up to that casting, initially at any rate, with a wilful determination to bend the coding of its traction control software to breaking point and inflicting a ride quality around town that’s marginally better than setting off down the Dipper after zipping yourself into a hard-shell Samsonite roller. Race mode has your foot bouncing on the throttle pedal like a Tullamarine taxi driver with St Vitus’s dance.

Read next: 2018 BMW M4 Competition LCI review

By contrast, the M4 feels as if Munich has commissioned Tempur for the damper tune. By most normal measures it’s still firm, but there is a degree of suppleness that’s missing from the Benz. The bandwidth between the M4’s Comfort and Sport+ settings isn’t huge, certainly less than the C63’s arc between acceptable and vertebra-clacking, while the Audi effectively has two damper settings. Comfort is where you’ll stay almost all the time, giving the RS5 a genuinely plush GT car ride, with Sport being reserved for smoothly surfaced twisties. On typically scabby country roads the latter will have your head coming into contact with the roof lining a little too often for comfort. Kiss goodbye to your sunnies if you occasionally prop them atop your noggin.

Snapper Wielecki has identified a suitably scenic corner for us to play on (33°33’18.22”S, 150° 8’36.31”E, if you’re interested), which requires a fair degree of commitment to make the cars look lively for his Canon. It’s here that the Mercedes shines, with just enough reassuring bodyroll and a beautiful, buttery transition into power oversteer.

Even with the ESC switched on, you can feel the electronic limited-slip diff smearing in and out, allowing just a spritz of rear end movement. In ESP Sport, it’s a whole lot more lenient, responding well to a gentle roll of the wrists. The weight of the engine makes itself felt if you’re lazy with your braking or ambitious with corner entry speeds but greater negative camber, stiffer bushings and a model-specific rear-axle carrier combine to give the C63 S a sweetly textural, benign feel at the limits of grip, belying its somewhat one-dimensional image.

Rolling from throttle to brake reveals a slightly clunky pedal positioning, Mercedes – like many manufacturers – retaining a higher brake pedal than accelerator; a legacy of manual car heel-and-toe requirements. Out of the corner, the Mercedes feels the strongest, with a comical slab of torque arriving at 3000rpm and persisting with no let up to 5000rpm. The AMG-Speedshift 7 lets you hold a gear if the requisite button is engaged, but despite its surfeit of cubic centimetres, the AMG engine operates best in that 2000rpm band and the gearbox software has a better feel for this than you or I. The optional ceramic front stoppers help shrug off the car’s 1725kg heft and, unusually for carbon picks, are easy to modulate, representing a key point of difference between Affalterbach and Munich.

The M4’s four-piston front brakes are the weakest aspect of its dynamic palette. It’s a perennial M-car complaint but BMW doesn’t seem to be listening, deeming them sufficient for fast road driving. That’s also open to question, the pedal going long after a few committed applications on a downhill stretch. The M4 also suffers from oversteer. Perhaps that needs qualification. Unexpected oversteer has given more than a few drivers a case of the frights and much of that may well be caused by the Active Sound symposer.

Read next: 2019 Audi RS5 Sportback pricing and features announced

Between 2500 and 3000rpm, the sound piped into the cabin is a muted, deep rumble. It doesn’t sound particularly potent, yet at this point in the rev range, the engine’s making its full slug of 550Nm; more than enough to light up the rears. BMW claims the symposer makes up 2-3 percent of the sound with the rest natural, but the careful wording of its claim is disingenuous. Listen to a car with the symposer disabled and it’s markedly different.

This is what’s spooked so many, the weird disconnect between what’s happening at their ears and what the rear contact patches are having to contend with. In short, oversteer arrives before you expect it and it’s spikier than the AMG, the BMW’s Michelin Pilot Super Sport rubber being less forgiving than the more malleable ContiSportContact 5P boots on the Benz, which exhibit a more manageably ramped transition from grip to slip. The M4 also has the loosest body control of the trio and requires a little more consideration when flicking from corner to corner.

Get into the RS5 after a committed blat in either of the other two and it feels as if you’re wearing noise-cancelling headphones. The Porsche-developed V6 (you’ll find similar ironmongery under the bonnet of the Panamera 4S) sounds a little too mannered, even when given a merciless prodding. I found myself clicking my jaw because I thought the altitude drop on the road had caused my ears to need popping. No, it’s just a lot quieter. Quieter and quicker. The numbers against the stopwatch tell a compelling story and there’s little doubt that on a gnarly cross-country route, the other two wouldn’t see where the RS5 had gone. It gives so much and asks for so little in return, which is both its greatest talent and most significant shortcoming.

The steering, even in Dynamic mode, is a bottle of Pure Blonde to the AMG and M4’s steins of Warsteiner. The front end of the RS5 is predictably mighty, with huge grip aided by the widest tyres of the trio, 275/30ZR20 ContiSportContact 6s. Try to get the car to misbehave and it all gets a bit reluctant, the 40:60 rear bias seeming to promise a level of throttle adjustability that the Audi isn’t keen on indulging. It’s undeniably effective at demolishing a string of corners, the new five-link rear end replacing the trapezoidal-link arrangement that underpinned the old car. It should be noted that Aussie cars feature the quattro rear sport differential – an option on Euro models – which delivers a greater percentage of fun to the outside rear wheel.

The V6 is freakish in its sheer relentlessness, with instant go from 2500rpm right through to the redline. There’s next to no let-up. The only automatic gearbox of the trio makes a solid partner, slurring up and down ratios almost imperceptibly, holding gears to the limiter if you prod the lever to the left and being way slicker in its operation than the stalk-mounted Benz shifter or the maddeningly over-complex BMW contrivance. Audi scores a minus point for getting the shift action the wrong way round though. And on an RS model too. Tut.

Charging Ahead: Audi E-Tron at Pikes Peak

The RS5 delivers the most refined cabin of the trio at cruising speeds, although loose chip surfaces set up some extravagant tyre rumble. The Mercedes is all exhaust boom, with or without the extra noise button engaged, while the BMW is largely civilised below 4000rpm, whereupon it all starts getting a bit exciting. While the Audi boosts its GT credentials with impressive driveline civility, it scores a few surprising ergonomic demerits.

The cabin is undeniably gorgeous, with hexagon-stitched leather seats, beautifully judged materials quality and that showstopper wall-to-wall TFT virtual cockpit. Spend a little time with the RS5, however, and its compromises become apparent. The drive select button, a function you’ll use fairly frequently, is tiny and a long stretch away, evidence of lazy right-hand drive conversion. After fumbling for that, you then have a few seconds to grab at the MMI controller dial before the screen reverts to its previous setting. What’s more, the buttons are all but impossible to see in bright light, nestling beneath a line of angled silver toggle switches that reflect the sun.

The seating position is also too high for a coupe, robbing headroom and exacerbating the shortcomings of the RS5’s ride quality in Dynamic mode. The manual steering adjustment feels a bit cheapjack after the other two’s slick electric rake and reach settings. Access to the rear is slightly better than the AMG and a good way worse than the M4, although once in, it feels snug and far from claustrophobic. The rear also has the best array of storage options, and it’s the only back seat of the three to get its own dedicated temperature control for the air-con.

The buttons to slide the front seat back and forth are considerately located on the upper side of the chair, unlike the M4 which positions them in plain sight on the back of the seat, which is always going to be too much of a temptation for evil offspring or drunken mates. Visibility out of the RS5 isn’t bad, with the slimmest A-pillars but the fattest B-pillars.

Styling? You’ll need to be the ultimate arbiter of that, but the Audi attracted a lot of interest. That complex, hue-shifting optional paintwork was a factor, but the RS5 is a striking car. It’s not as pretty as the original A5 shape, Walter de Silva’s finest moment, but it’s a confident and assured piece of vehicular sculpture. The AMG’s glitzy shtick will, for many, justify its elevated price tag. Great seats and showy alloys aside, the M4 looks slightly dull. This alone ought to be enough to guarantee the RS5’s success, from a sales perspective at least.

Read next: 2019 Mercedes-AMG C43 coupe review

We don’t count registrations as the fairest way of keeping score. We never have and never will, so it’s time to crown a winner of these three cars. The M4 is undoubtedly the most flawed of the trio, yet it’s a car that rewards an extended period of acclimatisation. What’s more, there’s real bite and character to it. Yes, it’s finishing this test third, but of the three, it’s the only one I reckon you’d grow to love, and it’s the only one that’s also offered with three pedals. The Pure model probably ought to be a simpler, rawer thing, and that car doesn’t exist as yet. The M4 CS shows what can be done but, to put it bluntly, its price is a joke, even allowing for its more recent haircut. Model by model, BMW continues to just miss with the M4, like a sniper repeatedly overcompensating the adjustment on a scope.

The RS5 is an interesting one. It excels on so many objective counts that were we totting up scores, it’d undoubtedly emerge with the biggest number. It’s the newest, slickest, most economical, and quickest on a challenging road, but it never connects with the driver on any significant emotional plane. It’s more ‘good Audi’ than bad, but it emerges as a bit of a curate’s egg: it’s a melange of overpolish in some areas and somewhat underdone in others. Its optimum ride/handling setting is, frustratingly, somewhere smack between the binary Comfort and Dynamic modes and that engine needs more attitude and flintiness to it.

Which leaves the Mercedes-AMG as last man standing as the other two manage to count themselves out. Yes, the ride could be better and the shouty design will dissuade some but, unlike both of the others, this is a car that doesn’t seem to take itself too seriously. This impishness is infectious and encourages you to have a little fun. It’s less one-dimensional than you expect which, admittedly, is not saying much, but it nails a brief that AMG seems to understand better than the others. It’s about an experience removed from the ordinary and the C63 S drenches you in just that from the first prod of the starter button. Notch another one up for Affalterbach.