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RE: Mercedes-AMG C63 vs. BMW M4

Monday 26th October 2015

Mercedes-AMG C63 vs. BMW M4

The classic M versus AMG grudge match moves into the turbo era - who does it better?

Ideally we'd have pitched this Mercedes-AMG C63 S saloon against the equivalent four-door BMW M3, not the coupe M4. But the latter was to hand courtesy of its presence on the PH Fleet and, arguably, AMG C-Classes are historically four-door saloons (or five-door wagons) and the equivalent fast 3 Series a coupe. Even if it's now a 4 Series by name. Mercedes only added a C63 coupe into the mix in the previous generation and we'll be driving the new one soon; as it stands BMW sells M4s to M3s at a ratio of nearly three to one.

M3 and M4 interchangeable in pace and character

To head off those saying it's not a fair comparison, a forensic examination of both spec sheets and technical data reveals one crucial difference between M3 and M4: without the head-up display added, the windscreen shade band is £60 on the four-door but standard on the coupe.

OK, there's a little more than that. Performance stats and technical features are identical for both cars but the saloon is £460 cheaper, 23kg heavier, 7mm wider, 47mm higher, has 58mm more shoulder room in the back and another 35 litres of boot space. Power to weight for a comparable M DCT equipped car is slightly behind for the M3, with 264hp/tonne against the M4's 266hp/tonne. Accepting the coupe has a slightly favourable centre of gravity and fractional power to weight advantage, in all other respects it's fair to consider impressions of the car's character as interchangeable between M4 and M3.

Which is a long way of saying, yes, this is a reasonable head to head, further enlightened with previous experience of both BMWs and the C63 on their respective launches at Portimao, plus road tests here in the UK.

Mercedes-AMG C63 S
The difference in character, traditions and mindset of these two cars is obvious from the first push of the starter button. Where the BMW growls away with an urgent, metallic sounding gargle the C63 is pure AMG; a clap of V8 thunder and then a menacing, bassy burble that'll rattle the windows the length of your street. As fluids warm and exhaust flaps close both settle down to a quieter tickover as you pull away. But those first 60 seconds or so tell you a lot about what each car has in store for you.

Comfy, luxurious and with just a whiff of chintz

And, frankly, may be what tips you one way or the other. In the AMG tradition, the C63 S remains a car dominated by its V8 engine. It might lack the 6.2-litre shock value of the last one but with another litre of capacity, two extra cylinders plus 510hp and 516lb ft of torque it absolutely thumps the BMW's 431hp and 406lb ft.

OK, it weighs another 95kg against a comparable M DCT M3 saloon and 118kg more than this M4, with both BMWs available as manuals weighing 40kg less still. But none of these cars can be considered light and (marginally) by the numbers and (decisively) by the seat of the pants the AMG feels the more potent and muscular car.

Huge punch, big character, great noise

It scores on the emotive factors too. Our introduction to AMG's M178 engine was reverent attention as we were played a succession of recorded Affalterbach V8s, culminating in the new 'hot-V' twin-turbo motor. And from that first fire-up and every mile that follows that bass is always there, tingling through the car, pulsating in your chest and scoring your every move. For sure, the sound has been engineered. But more naturally than the BMW and entertaining whether you're pottering around town at 20mph or flat out on a favourite B-road.

Only you won't be. Because flat out in the C63 is not somewhere you'll get to experience too often. It's a common refrain with modern performance cars but the C63's abilities so far outstrip any notional sense of what's achievable on the public road as to leave low-speed burbling your only option for enjoying the car. In the previous C63 this was offset by a rawness and response that engaged throughout the speed spectrum. But the new C63 is a much more grown-up and mature vehicle; plusher, grippier, more opulent and perhaps a bit more Mercedes than it is AMG.

A little tame next to the M car?

We've seen the same in the evolution from SLS to GT. The older cars were 'flawed' and the newer ones 'better'. But the multi-mode dampers and active diffs in both GT and C63 take the appealing rough edges off. Where the proactive (optional) mechanical diff on the previous C63 cut in before the ESP, the new active one works in collaboration. In the old C63 with the systems fully on you could feel the influence of the rear axle, even if it was as subtle as a slight lightening of the steering through transitions.

Now that huge power is delivered in partnership with all the other systems, meaning you have to be surprisingly lead-footed before any meaningful sense of rear-driven influence kicks in. In engine size and driving style no longer does it feel as over-endowed as the old one. Light steering only adds to this sense of disconnection. Initial softness in the throttle as the turbos spool up doesn't help, though the AMG's extra cylinders and capacity blurs the transition between on and off boost better than the BMW's six. The AMG's steel brakes are slightly easier to modulate than the BMW's expensive optional ceramics; Merc offers the same as an option but for road use they're more than up to the job.

Want a fast wagon? Only Merc caters

As a place to be the Mercedes' character is very different from the BMW's too. It's a much more opulent and lavish cabin, kitsch almost in its use of chrome and other trim highlights. It's also quieter and more comfortable and the damping is much more assured, with iron-gripped body control but also a sense of float and flow. As ever with multi-mode cars after much fiddling and configuration you usually end up settling on the mid-settings for everything and leaving it there.

BMW M4
Both downsized, both newly turbocharged, both facing an uphill struggle to win over long-time fans ... arguably this is the first time M and AMG have converged on similar ground after generations of cars built to very clear and different templates. Indeed, having out as a homologation special built to battle Mercedes on the track, the M3 has over generations got closer to the AMG template as it's gained cylinders, weight, complexity and size. And here we are, both brands now offering forced induction, multi-configurable driver modes aplenty, all the latest gadgets and tech and a broader than ever operating window.

Complex in character, S55 motor feels racier

In comparing a coupe with a saloon you'd inevitably expect the M4 to feel more low-slung, sporty and aggressive than the C63, which it does. But the M3 isn't shy either, thanks to cartoonish rear arches swollen to accommodate the M4's wider rear axle and a similarly sportlich seating position and ambience. It's not just the colour that makes the M the more extrovert car - even in the more subdued Black Sapphire of the M3 saloon we tested last year the BMW is a feistier, more aggressive machine.

When you look at the baseline figures of the respective entry models the BMW's power deficit does look a little worrying though, the 431hp M3 costing £56,595 against £60,060 for the 476hp non-S C63 saloon. Factor in the M DCT dual-clutch to put it on equal terms with the Merc's seven-speed 'MCT' auto and this narrows to £59,240 though. As tested the initially more expensive sounding Mercedes again narrows the gap, this fully-specced 510hp S saloon costing £73,020 against our M4's £73,870. Ultimately both are expensive cars with many and varied ways to make them more so; prospective owners would do well to spend time on the configurators and cost up each to their desired spec before deciding which ultimately represents better value.

M4 cabin has sense of purpose; well made too

On the road that on-paper performance gap becomes less relevant, not least given the limited opportunities to exploit the upper limits. But perhaps more so because of the vastly different characters.

Remember that point about the noise? The BMW backs up this first impression every step of the way by being far more aggressive and pointy than the AMG. You can read more about impressions of the engine's character in the PH Fleet reports but that initial spike of boost dominates the power delivery and the way the chassis puts it to the road. And if you can successfully mitigate the destabilising effect of the turbos spooling up the M engine has a broader and more rev-happy operating window than the AMG V8. If only it sounded better doing so, the artificial blare never convincing yet always intrusive.

Unlike the C63, you're never in any doubt about where the power is going either. The diff locks up far more aggressively, the rear axle always wants to dominate the proceedings and though the variable rack steering is a bit mushy off-centre the front-end dives assertively for the apex, meaning the rear is never far behind. Or ready to overtake. We've said it many times before but this turbo M car has the potential to be a serious handful, which may or may not be to your liking. Contrived or otherwise, this is the more hardcore car by a long shot.

Verdict
Traditionalists will prefer the older versions of both of these cars. These new ones are almost caricatures, using gizmos and configurability to deliver a digitally enhanced impression of what went before. With a better CO2 figure.

Merc probably better, BMW more thrilling

The good news is there substance behind all this though, the engineering that underpins both cars showcasing the experience, traditions and skill of both brands in fine style. It's just a shame you have to push so far beyond the realms of what real world driving allows to appreciate them.

It's a close one too. The Mercedes is way more charismatic thanks to that engine and it's generally warmer demeanour. The damping is way more sophisticated and nuanced than the BMW's too and it's a nicer place to rack up the miles, with the appealing option of an estate if that's your bag. And those huge reserves of power and torque are enough to silence pretty much any protest, including what seems like an initially higher price. Objectively it's probably the better car and more able to slip under the radar when required.

And the gold medal goes to...

But the flaws are what make the BMW more interesting and entertaining. It's not necessarily an easy car to get along with and understanding and exploiting its talent takes some learning. On a wet road late at night it might well scare you silly. The synthesised engine noise frustrates and whatever mode you have the dampers in the chassis never feels entirely at ease. But its sheer ferocity is intoxicating, the looks are more cohesive than the Merc and arguably better still in saloon form. Clearly optimised for the M DCT gearbox, there is that manual option to add curiosity value for the diehards. On this showing, and with previous experience of both cars in their different variants on road and track, the BMW would be our pick.

MERCEDES-AMG C63/C63 S SALOON
Engine: 3,982cc twin-turbo V8
Transmission: 7-speed auto with lock-up clutch (MCT), rear-wheel drive
Power (hp): 476@5,500rpm/510@5,500rpm
Torque (lb ft): 479@1,750-4,500rpm/516@1,750-4,500rpm
0-62mph: 4.1sec/4.0sec
Top speed: 155mph (limited)
Weight: 1,715kg/1,730kg (EU, with driver)
MPG: 34.5mpg (NEDC combined)
CO2: 192g/km
Price: £59,795/£66,550 (C63 S Saloon as tested £73,020 comprising Premium Package interior with Artico leather dash, Nappa leather look door linings, Keyless-Go with keyless entry/start and powered bootlid, Burmester surround sound system, LED Intelligent Light System and panoramic electric sunroof £2,595; Driving Assistance Package with Blind Spot Assist, Distronic Plus cruise control, Lane Keeping Assist and Pre-Safe £1,495; Brilliant Blue paint £646 and 19-inch AMG forged wheels in black £1,735)

BMW M3/M4
Engine: 2,979cc 6-cyl twin-turbo
Transmission: 6-speed manual/7-speed dual-clutch auto (M DCT), rear-wheel drive
Power (hp): 431@5,500rpm
Torque (lb ft): 406@1,850-5,500rpm
0-62mph: 4.3 sec (4.1 sec M DCT)
Top speed: 155mph (limited)
Weight (M3): 1,595kg (1,635kg M DCT, both EU, with driver)
Weight (M4): 1,572kg (1,612kg M DCT, both EU with driver)
MPG: 32.1mpg (34mpg M DCT, both NEDC combined)
CO2: 204g/km (194g/km M DCT)
Price (M3): £56,595 (£59,240 with M DCT)
Price (M4): £57,055 (£59,700 with M DCT, M4 Coupe as tested £73,870 comprising £1,330 for Black Merino leather, £545 for advanced parking package, £2,645 for M DCT transmission, £6,250 for carbon ceramic brakes, £175 for 19-inch M Double-spoke style 437M alloy wheels/Black with mixed tyres, £265 for sun protection glass, £155 for extended storage, £140 for sliding front armrest, £440 for lane change warning system, £395 for Carbon Fibre interior trim, £1,600 for Adaptive LED headlights, £370 for driving assistant, £500 for surround view, £825 for M Head-up display, £675 Harman/Kardon Loudspeaker system, £95 internet and £190 for online entertainment)

C63 vs. M4 pics: Chris Teagles

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