Audi RS5 vs Mercedes-AMG C63 S twin test review | CAR Magazine

Audi RS5 vs Mercedes-AMG C63 S twin test review

Published: 02 October 2017 Updated: 02 October 2017

► Two premium super coupes
► Both with big bhp twin-turbos
► 913bhp twin test on road and track

We’re in prime Audi territory: blissfully clear early evening motorway, inside lane at a solid 75mph, miles digitally 
recorded and discarded just as quickly. The climate is spinning silently at 19 degrees, the auto ‘box is locked in eight and there are barely 2000 revs showing; I feel like I could drive until the road runs out while using just a fraction of the Audi’s ability. Like undercover special forces it is quiet and calm but 
perpetually prepared with punches of acceleration and kicks to the kidneys. Is this the ultimate do-anything sub-supercar?

Click here to read CAR’s online review of the Audi RS5

Audi RS5 Mercedes-AMG C63 S

The answer lies somewhere in the rear-view mirror. The 
Audi’s window tints shift the colour of the C63 S from dark blue to moody black, jacking up the visual threat still further. From the front, the Mercedes is a square-jawed security enforcer squeezed into a suit deliberately tailored half a size too small, its daytime running lights providing wickedly upturned eyebrows as it bobs over motorway undulations. The sense of calm readiness in the RS5’s cabin has been punctured by the Merc’s rumble-ready face. Audi’s new boy has work to do.

Click here to read CAR’s original review of the Mercedes-AMG C63 S Coupe

Audi RS5: V8 RIP, but new V6 brings more power and less thirst

The new RS5 (B9, code jocks) has already proved itself a deeply capable and impressive machine on a solo drive. Ditching the best part of the old car – the engine – was either brave or stupid depending on your point of view, but a turbo motor is now as much of a given as air in the tyres. For all the old V8 brought in terms of character, the new V6 kills it on paper; torque is up by a staggering 125lb ft, fuel 
efficiency up 17%, weight down 60kg and the 0-62mph time is now under four seconds – no engine note can silence the roar of this engineering victory.

Audi RS5 engine

Straight-line wins will never be enough, though, and Audi has taken the significant step of optioning all UK-spec cars with the sport differential, giving more twist to the outside rear wheel. Add that to the 40:60 front/rear torque split and the intention is clear: the RS5 is designed to win on all fronts.

AMG C63: still a V8, but no longer naturally aspirated

Even against AMG’s C63. Good luck. Where historically AMGs could be relied upon for unholy performance, more recently they’ve acquired a chassis to match, thereby cementing a deserved reputation for outrageous entertainment with all-round brilliance. That said, it’s still the engine that takes centre stage – a sufficient indication of its magnificence is that it almost makes you forget about the old 6.2, which was one of the finest production engines of the last 20 
years. Not only that, the V6 asks that you feed it less often while delivering 99% of the thrills. In the C-Class the addition of the S brings that extra power and torque and an electronically 
controlled rear diff instead of a purely mechanical one. The purist in you might grumble, but the two combine to help the C63 S dip below four seconds to 62mph. That’s not the only trick up its sleeve either, so save your whining.

Design: taut creases vs bulbous bulges

The two meet for the first time in what you might term premium territory. The Cambridgeshire town of Kimbolton has a bias towards Tudor buildings and fee-paying schools, but while the brands dovetail with the location, these cars are far too loutish to blend in.

Audi RS5 Mercedes-AMG C63 S

Visually it is the Audi that draws the eye. Where the regular A5 wears its discretion and sobriety like the office dress code, the RS5 adds layers of details that blend into controlled drama. The Nardo Grey paint is solid rather than anything fancier and is a free hit, but it’s worth recognising the work done by the carbon black styling pack (£5k), 20-inch five-spoke alloys (£3k) and carbon roof (£3250). It’s what configurators were made for – maybe you can make one look equally as ripped and 
hard-ass without £11,250 of upgrades, but this one looks bloody terrific. Its swollen arches and pinched midriff nod to the Ur-Quattro, while  purposeful flicks of carbon picking out some tasty detailing. Lean and toned from all angles, the balance is nicely judged: to lay your eyes on it is to want to drive it, but your mum won’t mind it parked on her drive.

The Mercedes might trigger her vocal disapproval. Finished in relatively discreet Brilliant Blue (£645) with optional gloss black alloys (£1735) it is all aggression from the front, steel-jawed and shoulders square, but there’s a curious imbalance to the shape, as the strong crease down the flanks leads into the truncated rear, like there was a shortage of sheet metal by the time they got to the back end. Take a stroll around it and some angles are clearly better than others. The faintly retro-tinged styling cues seem to suit bigger Mercedes-AMG cars well, but in a size C it’s neither as clean nor as sophisticated as you might expect for your £70k and up. It’s a clear win for the 
Audi in round one.

How do these cars cope with urban drudgery?

We’ve not even left our parking spots on the high street and the Audi and AMG are doing things differently. Prod the RS5’s starter and you get an orchestrated flourish of revs before it 
almost instantly settles to tickover; enough to prick up the ears but shy of Neighbours From Hell.

Audi RS5 Mercedes-AMG C63 S

The AMG on the other hand has discretion electronically ruled out from the start. You can fiddle with the drive mode 
if you like, but in comfort the exhaust is loud, and in 
race mode it’s profanity-inducing. There might be times in your life when you long to find a shush button tucked away somewhere on the centre console, but more often than not the AMG V8’s barely-controlled brio boosts your mood. Both cars beg to be driven hard but the C63’s siren-like call is dangerously hard to ignore.

If this were a boring publication I’d make a great fuss about how challenging these two cars are to drive in stop-start urban traffic, but thankfully it isn’t so let’s discuss it appropriately. Cars like these are bought by people who want to have fun, but unless your postcode equates to Stowe corner, you inevitably have to drive through urban sludge to get there. And the Audi is pretty brilliant at this. Both cars have several drive modes plus the option to create your own mix of settings, but even when you’ve got it all turned up to the max while negotiating poorly planned traffic management, the RS5 doesn’t make it hard work for you.

Audi RS5 Mercedes-AMG C63 S

Specified here with dynamic steering, the RS5 will play the town kart, requiring only slight rolls of the wrists to lap mini-roundabouts while S-tronic makes you forget it even has a gearbox. That V6 is as docile as they come too, leaving you a nice wodge of torque at low revs so you don’t have to poke it to get going, but without making you tiptoe for fear of unleashing the Kraken.

It’s not that the Mercedes is particularly hard work in the same circumstances but you do have to be a little bit more careful. Those of an indelicate right foot will probably not get on with it; even in the softest drive setting, the full 516lb ft of torque is just 1750rpm away. But once you’ve recalibrated your brain there’s fun to be had, trickling along in a stupidly low gear and making shop windows vibrate.

And what are they like when they’re set free out of town?

Childish japes aside, we’re bored stiff of keeping these cars hemmed in by traffic. They are as capable here as the more modestly powered versions lower down the range, but you wouldn’t shell out upwards of £70k for a mobile armchair. Crabby, inconsistent and obstreperous B-roads are the true playground for cars like this, and it’s their ability to turn left out of the office and deliver big-money thrills as soon as you hit second gear that makes them desirable.

Up the pace out of town in the RS5 and the ride is more 
settled. Leaving the drive mode button untouched, a progressive squeeze of the Audi’s throttle brings layers of response. There’s no delay in the turbos spinning up, a firm push forward as the revs rise and effort redoubled as the S-tronic drops a gear. By the time your foot is to the floor, the RS5 is singing, a complex and intriguing warbling coming from the exhaust.

Of course it’s fast, but it’s a controlled, measured shove that builds until you start to swear and think about braking. You can rev it out and shift manually and it will comply with glee but there’s more appeal in its sheer efficacy, grabbing bursts of acceleration between dabs of brakes. It feels invincible, finding speed with composure where you think there’s none left to be found – a true quattro Audi, then.

But there’s no shaking the C63. You have to work harder for it in some respects, not least because indelicate hits of wide-open throttle will get you either admonishing blinks from the ESP or some crude rear-wheel steering. In a straight-line fight between the two there’s nothing to separate them, as the 
higher output of the AMG is offset by chunkier kerbweight.

Audi RS5 Mercedes-AMG C63 S

How the C63 goes about pressing on is substantially 
different though; you’re never alone in the AMG because that V8 has so much charisma and so much to say it could anchor Saturday Night Live. It dominates the whole character of the car and, for better or worse, it feels like the rest of the C-Class was designed to fit around it.

On a cruise it burbles with acceptable quietness but you can never escape the feeling that it wants to be let loose, to rev out and raise merry hell. The right gear is the gear you’re already in – just push to go. Do it in a high gear and the volume doubles while the pitch starts to climb as the acceleration builds, the speed at which you’re travelling seemingly at odds with how slowly the motor is spinning. Its beautiful linearity plays out all the way to the redline, the roar from deep within seems impossibly illegal and full attention is demanded by the ease at which it piles on big speed. Utterly addictive, the C63’s V8 is easily capable of bringing out the worst in you.

…and on the track?

There are still questions for these cars to answer, and in the interests of respectability the track is where we’ll find them. These aren’t track cars; you tend not to specify fine leather and heated seats if you lie awake memorising braking markers. But both marques like to draw on their motorsport exploits and no doubt some owners will take the opportunity to cut loose within strictly defined regulations.

Historically, fast front-engined Audis and circuits weren’t made for each other, with the four-wheel-drive layout the main culprit. But the RS5 has that tweaked torque split and sport differential to shift the balance in the right direction. And it works. Drive it with a little in reserve and all the elements blend together beautifully; the quick steering boosts the impression of agility and never robs you of feel, the brakes are instantly firm underfoot and the underlying balance is clearly there.

With the braking all done and pitched into a bend on a trailing throttle you can feel both ends of the RS5 working. Even when loaded up, understeer is resisted, and adding or removing 
power subtly shifts the angle of attack; this is a three-dimensional car where the old version was too stubborn to take any notice of your inputs.

Audi RS5

There is also – believe it when you feel it – a degree of oversteer to be exploited. Out of slower corners full-attack mode delivers surprisingly extravagant four-wheel drifts instead, but through medium- and high-speed turns it will start to push from the rear if you shut down the power, and getting back on it will hold it there, albeit briefly. On those occasions, when you have the space and the inclination, you might decide  that the RS5 delivers all the rear-end silliness you’d like.

Driving the C63 S might change your opinion, however. If the bark of the AMG’s motor and the bite of its performance suggest it is some kind of wild beast, its behaviour when 
slightly over its limits proves otherwise. It’s actually sufficiently mannered and controllable that it will perform tricks and let you tickle its metaphorical belly.
On track it feels faster than the RS5, even if it is down to the increased drama rather than any measurable advantage, and although the steering is slower than the Audi’s, its consistent accuracy is reassuring when you have more pressing issues on your mind. Use the same approach on your way in and there’s a similar absence of understeer unless your ambition outweighs the available grip. What happens next is entirely in your hands, or more accurately, under your foot.

Mercedes-AMG C63 S Coupe

A smidge of throttle keeps it neutral, a little more and the nose starts to push on. Add any more power and rapid wheel-swivelling becomes essential, but even this can be finely managed. In ESP Sport mode you can have small to medium slices of oversteer before the electronics start to reel you back in and even with it switched all the way out you can exit a corner fast and hard, checking the slide with ease.

What it will do that the Audi can’t is play the total loon. Brake hard, pitch it in aggressively and tramp the gas, then pick your clipping point; it’s as easy to hit an apex with the AMG all crossed up as when you’re doing it by the book. It will go hilariously, outrageously and unendingly sideways, the electronically managed diff seeming to read your mind and fulfil any ’70s rally car fantasy. How often a prospective owner will engage in such tyre abuse is neither here nor there: it surely only adds to the desirability of the C.

Verdict: RS5 the best car, AMG the most fun – either way, you win

After squeezing every second of track time and with just enough rubber remaining to get us home, the R and the C are going their separate ways. Returning to the Audi and its 
virtually flawless cabin, I know this is the place I want to be right now. I’m also fully aware that for the whole day, the best car has been the one I happened to be sitting in. With two hours of cross country, A-road and motorway mix ahead, the RS5 will get me there quickly, discreetly and still be fun. The same journey in the AMG would be just as fast, much more conspicuous and harder work, but likely even more of a blast.

The Audi is brilliantly competent in so many areas. It’s the car you’d want on your driveway, the one you’d want to crawl into after an unholy early start, to drive across Europe for a 
holiday, to take the kids to school. In each of those scenarios the AMG is perfectly capable too, just a fraction more hard work. But when you’re really peddling along it is the first choice here, even if it requires a little more care when you do. So how do you choose a winner? Simple; you pick the one you want.

Audi RS5 Mercedes-AMG C63 S


Mercedes-AMG C63 S Coupe
> Price £70,190
> As tested £84,070
> Engine 3892cc twin-turbo V8, 503bhp @ 5500rpm, 516 lb ft @ 1750rpm
> Transmission 8-speed auto, rear-wheel drive
> Performance 3.9sec 0-62mph, 155mph, 32.8mpg, 200g/km CO2
> Weight 1800kg
> On sale Now
★ ★ ★ ★ ★

Audi RS5 Coupe
> Price £62,900
> As tested £91,775
> Engine 2894cc twin-turbo V6, 444bhp @ 5700rpm, 443lb ft @ 1900rpm
> Transmission 8-speed auto, all-wheel drive
> Performance 3.9sec 0-62mph, 155mph, 32.5mpg, 197g/km CO2
> Weight 1665kg
> On sale Now
★ ★ ★ ★ ★

Mercedes-AMG C63 S Coupe

By Matt Joy

Former associate editor of CAR magazine