BMW M4 vs Mercedes-AMG S63

What's the difference?

Brutal, bruising and utterly brilliant, the M4 CS will be an acquired taste due to its no-compromise approach, but those willing to take the leap will find a performance car like few others at their disposal.

Both of these vast vehicles are phenomenally comfortable - this is the kind of car that Mercedes does so well, and has done for decades. The S Class is rarely a disappointment but it's difficult to believe that such a big, heavy GT car can also dance the way the S63 does.

The S560 is far more weighted to being a GT - supremely comfortable with that active suspension, a growly, refined V8 and a cabin full of gadgets and comfort. The S63 is altogether more aggressive, to look at and to drive. Lopping the roof off both of them adds weight but, like any cruiser, also puts you out in the sun, the breeze and into your surroundings. Plus, in the case of the S63, you get more exhaust noise.

They're two very different cars and not just because of the engine. After all these years admiring it from afar, the S63 has delivered on my teenage expectations - fast, smooth and utterly mad.

The M4 CS is familiar in all the right ways, but definitely looks significantly jacked up compared to its lesser siblings.

Part of that is the extensive use of carbon everywhere, from its bonnet panels to its roof, front lip, side skirting and boot spoiler. But also because of its super-muscular angles and creases, including the huge dome in its bonnet.

Also exclusive to this M4 CS is the light treatment, with the front LEDs lighting up with yellow highlights the brand says are supposed to be reminiscent of GT racing cars.

At the back, the rear lights are flush with fibre optic lighting, lending a flowing and unique light signature that looks epic at night.

Inside, it's a sea of carbon, with the lightweight racing seats, the dash inserts and the centre console all lined in it. It is a perfectly finished space, though, and one that's also flecked with red, including a 12 o'clock band on the thick-rimmed steering wheel, the seat backs, the contrast stitching and the paddle shifts.

Be warned, though, it takes some acrobatics to climb into or out of the CS. The seat bottoms have these super high edges that double as grab handles, but require some awkward contortions to navigate.

In short, it looks angry, this M4 CS, inside and out.

The S Class Coupe is obviously related to the sedan but manages a svelte appearance. Slimmer hipped and with a more Coke-bottle shape, the Coupe - if you squint a bit - has a bit of the classic old pagoda about it. Obviously you can't do pillars that slim anymore, but the glass roof takes away some of the visual weight inside and out. 

The cabriolet's roof is nicely integrated and looks good when it's  up, which isn't always the case.

They all look long, though. It's obvious to see why the cars all run on 20-inch wheels - anything smaller would look hilarious.

The cabin is a fairly sensible re-imagining of the E-Class. The big twin-screen layout of the dash and multimedia system seems a bit more at home here. The chintzy Burmester speakers in the doors let down an otherwise classy cabin, which steers clear of otiose vulgarity in looks and materials.

It all boils down to how you classify practicality in a car like this. I mean, the basic stuff is all there – it's got two doors, four seats and a boot capacity of 440 litres.

It measures 4801mm in length, 1918mm in width and 1399mm in height, and room for front seat riders is good, but less so for anyone you squeeze into the back. There are even ISOFIX points for a child seat.

But if you consider practicality the practical pursuit of performance, then the M4 CS has plenty of perks.

Well look, if you end up in the back of the S Coupe, it's not a riot of space. Obviously it has back seats (the SL doesn't even squeeze a jump seat into its considerable length) but they're for occasional, if luxurious, use.

The boot is a reasonably decent 400 litres, obviously the cabriolet loses a few litres with the roof folded. Front and rear passengers will both enjoy a pair of cupholders and the whopping long doors will each hold a bottle.

One thing hasn't changed in nearly 20 years - the S isn't cheap. Available in coupe and cabriolet, the S560 starts at $314,900 for the former and $336,900 for the latter. Step up to the S63 pair and you'll pay from $370,500 for the coupe and $399,900 for the cab. If you're super keen for something spectacular, the twin-turbo V12-powered S65 is available for between $508,900 and $520,500, and features Swarovski crystals in the headlights, for some reason.

As you can imagine, there's quite a bit to cover, so for both cars I'll stick to the edited highlights. The S560s roll on 20-inch alloys, has a 590-watt 13 speaker sound system, digital TV, auto parking, active cruise control, panoramic glass roof, Nappa leather, active seats and power-closing doors.

It also comes standard with a heating pack that not only heats the seats but the steering wheel and centre console. In the cabriolet you also get the 'Airscarf' neck heater.

Both cars also feature's Mercedes' Magic Body Control with curve function. More of that wacky feature later.

The S63 AMG is a step up in power, price and spec. One notable change from the S560 is the loss of 'Magic Body Control', which is replaced with mere air suspension. The 20-inch alloys are 10-spoke forged units, the brakes higher performance composites with red calipers, while an AMG sports exhaust brings the noise.

Naturally, both are swathed in high-quality leather and feature dual-zone climate control, heated and cooled electric seats that adjust in every direction, deep carpets, keyless entry and start, fully digital dashboards and just about every gadget to which you can point your imagination.

Entertainment and sat nav are via Mercedes' 'Comand' system, which is displayed on a massive 12.3-inch slab of glass at the top of the dashboard. The 13-speaker Burmester-branded system is predictably impressive and with Apple CarPlay and Android Auto, you only have to use the basic software for the radio or various car controls.

BMW has found yet more grunt lurking in its trusty 3.0-litre 'M TwinPower' six-cylinder petrol engine, with the M4 CS now pumping out 405kW and 650Nm.

That's a decent jump from the 390kW and 620Nm served up by the M4 Competition, and a giant leap from the outputs of the 'base' M4 – 353kW and 550Nm.

Predictably, then, the CS is the fastest of the lot, knocking off the run from 0-100km/h in 3.4 seconds, compared to 3.5 and 4.2 in the Competition and M4, respectively. The top speed is also dialled up to 302km/h.

All that power is channeled through an eight-speed automatic and sent to all four wheels on demand, with the help of an 'Active M Differential'.

All four coupes and cabriolets ship with Daimler's formidable 4.0-litre twin-turbo V8. The S560 scores 345kW/700Nm to drive the rear wheels through Benz's own nine-speed automatic. With all of that available, the S560 will crack the ton in 4.6 seconds and make a wonderful racket on the way.

Moving on to the S63, the same engine delivers a massive 450kW/900Nm. The run from 0-100km/h is dispatched in just 3.5 seconds and if I thought the S560 made a good noise, the S63 with its standard sports exhaust makes a better one. Again, Mercedes' nine-speeder is along for the ride.

The M4 CS is fitted with a 59-litre fuel tank, which – given the BMW's official fuel claim of 10.2 litres per hundred kilometres – should deliver a driving range on a full tank of 541 kilometres.

But... BMW also says the regular M4 – you know, the one that makes 52 fewer kilowatts and 55Nm less torque – uses 10.1L/100km, so do with that information what you will.

The lower-powered 560 drinks 98RON at the rate of 8.5L/100km for the coupe and 9.9L/100km for the heavier cabriolet.

The S63 ups the ante with 9.9L/100km for the coupe and an identical 9.9L/100km for the cab.

Our launch program contained some...er...spirited driving, which would explain the mid to high-teens fuel figures.

The hardest and angriest M4 of all time is, perhaps unsurprisingly, hard and angry. This is a race track specialist, but because I don't happen to own one of those, my first experience with the barking (and barking mad) M4 CS was navigating my way back from BMW's inner-city dealership.

Like it or lump it, you're going to read some Porsche comparisons here, because you're talking not too far off base 911 Carrera money, and suddenly I find the two Germans doing battle for a spot in my dream garage.

First things first, the BMW won't be much chop for daily driving for most people. Happily, I have a sickness for uncomfortable sports cars. It tells me that no compromises have been made in the pursuit of punishing performance.

A good thing, too, because the BMW, at city speeds, can be punishing. Everything feels heavy, the seats aren't overly comfortable – especially the hard bits that tend to dig in when cornering – and it stiff-arms its way over road imperfections, that exhaust booming and barking as it does.

Again, I loved it, and you probably will, too. But it's still not the kind of car I'd relish sitting in the morning peak hour rush in.

But escape the confines of the city and the BMW M4 CS suddenly makes a whole heap of sense. The acceleration is genuinely brutal, and wonderfully theatrical, with that quad-tipped titanium exhaust barking and snarling as you rocket towards 100km/h.

The steering is brilliant, with feedback fed to your wrists via that thick-rimmed wheel, and the entire experience feels sharp, super engaging and edgy.

You can push the M4 hard and fast, and I'm certain my limited talents would run out far before the BMW's would, but there's this thrilling sense of peril sparked by the aggression of the experience, that I love.

It's like the magic of a roller-coaster, I guess. Even if you know nothing is going to happen, you never really know, right? And in that lies the magic.

But back to original question, this or a Porsche 911? There's no doubt a Carrera is a better all-rounder, in terms of comfy commuting and race track fun, but this angry M4 is all shouty theatrics, all of the time.

I bloody love it.

Let's start with the S560. That smooth V8 rumble is all you'll ever hear if you just slot into drive and go for a leisurely spin. The nine-speed automatic continues to be a revelation to me - in the GLC63 it's good and here, once again, it's excellent, finding the right gear for the occasion and riding the fat torque curve. Other nine-speed autos are not very good at all.

The test route for the S560 played to the strengths of the car. It had some lovely winding roads, which brought the trick suspension into focus - the Magic Body Control with curve function is hilarious. While the active suspension works hard at all times to ensure the ride is smooth and drama free, the Curve mode (no, really) actually leans the car into corners.

Those of you who remember the video game Wipeout 2097 will be big fans of Curve mode. As you approach a corner, you turn the wheel and then the car leans into the bend. This isn't active damping reading the road, it's the outside suspension lifting the car and the inside lowering it, so the car feels like it's gliding, like a hovercar. It's wild but oddly calming. Mercedes reckons it's great for those who get car sick. As I didn't have my wife on hand to test this theory - she chucks at the first sign of a corner - I couldn't verify this claim. That will have to wait.

The S63 AMG is a completely different proposition. The air suspension is more than up to the job of helping smother the effects of the car's considerable weight, meaning that no matter what you're up to, the car feels reasonably light on its feet. It never feels small, though, commanding the respect of the driver and plenty of space from other road users.

And boy, do you need some space if you kick the S63 into Sport mode. In true AMG style, the electronic reins relax and the big luxury coupe cheerfully kicks off. The tail will wriggle under an unsympathetic right foot, that signature V8 roar, crackle and hiss filling your ears. The S63 is always the harder-feeling car, but it delivers with a more sporting drive than the S560.

Being the generous soul I am, I volunteered to return the S63 to its home for the evening rather than consign it to the back of a truck. On the back roads I took to reach the highway, it was rock solid - fast, predictable and a lot of fun. Once I found the boring straight bits, it turned into a supremely comfortable cruiser, ticking along in ninth at the legal limit (and being Melbourne, it was very much the legal limit), dispatching overtaking with barely a flex of a toe. 

The active cruise took the stress of keeping away from the State Revenue Office's clutches while being quiet and utterly pleasant.

The S-Class coupe comes loaded with eight airbags, ABS, stability and traction controls, forward and reverse AEB with pedestrian detection, reversing camera, crosswind assist (I know, right?), traffic-sign recognition and reverse cross traffic alert.

The S-Class Coupe does not have an ANCAP or EuroNCAP rating.

The M4 CS is covered by BMW's five-year, unlimited-kilometre warranty, with condition-based servicing available in packs, which will cost you $3530 over five years/80,000km, or $2900 over four years/60,000km.

Mercedes offers a three-year/unlimited-kilometre warranty with roadside assist for the duration.

The company also offers both service plans (where you pay up-front as part of the vehicle purchase) and capped-price servicing on the coupes. Servicing over three years is in the order $2500.