What's the difference?
Big sedans are not in vogue at the moment and huge luxury sedans were on the way down before the humble Commodore and Falcon departed the upper end of the sales charts. The Germans, who have always done a spectacular job of these flagship sedans, cheerfully persist with these cars.
Absolutely loaded with fascinating technology that bleeds its way down to the more mainstream models, they represent the zenith of the brand's innovation and style. The A8 is certainly that.
What it isn't, is particularly sporty, but after two years since its launch, V8 power has reached the fourth-generation super-sedan to deliver the latest iteration of the iconic S8.
To say the BMW M4 CS is a hot ticket in Australia is something of an understatement.
Consider this. There is an even more expensive one, the M4 CS Edition VR46 – at a cool $346,900 – and it sold out in less than an hour. Now, granted, Australia only got four examples, but still, demand was running hot.
That car makes this one, the regular M4 CS, seem like an absolute steal. It's only $254,900 (yes, the word 'only' is doing a lot of heavy lifting in that sentence), and it shares the same upgrades, and makes the same monstrous power, as the VR46 – for Valentino Rossi’s 46th birthday – only it does it for around $100K less.
See? A bargain. At least, that's how I'd be justifying it to myself if I had a quarter of a million burning a hole in my pocket.
So, this or a Porsche 911? Read on.
The S8's existence is a source of joy for me because it's not a huge SUV. Yes, it's a huge sedan but it's a reminder that the technological flagship is alive and well, at least in Germany. And the important thing about these cars is the way the toys filter down through the rest of the range. That used to take years but we're seeing this cool stuff a lot more quickly, right down to the A1.
The S8 punches, and punches hard in this rarefied part of an already shrunken section of the market - the twin-turbo V8 matches its German rivals, it's lighter and it's as well-stacked as any of the three. What it doesn't do, however, is shout about itself the way the other two do. It's the incognito choice.
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.
The sheetmetal is obviously very restrained given it's an Audi first, and secondly, it's just not done to go wild in this part of the market.
It's an A6 that's joined a gym, but didn't join that weird gym with men that can't run after you when you insult them (don't ask how I know this). Rolling on 21-inch wheels as standard, you can go up to massive 22s if you so choose.
The A8 created a subtle redirection of Audi's passenger car look, with the updated A4 and A6 both picking up on the horizontal bar between the rear lights and the huge grille framed by family lights with signature DRL patterns. The S8 builds on that with subtle S cues but nothing even vaguely shouty.
The interior acreage - or 'cabin', if you will - is very comfortable, but you already knew that. The multi-screen layout was first seen in the A8 and has now found its way into A7, Q8 and Q7 and is, as ever, brilliant to look at and use.
The MMI updates that have found their way into other cars are present and correct. Like the exterior, it's very restrained but not to the point of sparse minimalism, despite the lack of switches and buttons.
I really don't like the steering wheel, though, and I can't put my finger on why. It certainly isn't especially sporty-looking but I wonder if the standard flat-bottomed S wheel just looked stupid.
The materials are beautiful and everything fits together perfectly.
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 cabin is clearly built with rear seat passengers in mind, with rear leg and headroom configured for those continent-crossing drives.
The S8 has plenty of comfort for two rear seat passengers and a few amusing options to while away the hours in traffic or on the autobahn.
That doesn't mean the front seat passengers are in purgatory, with huge but supportive seats adjustable in all conceivable directions.
Front and rear rows score a pair of cupholders and bottle holders while the boot is a handy, if not awe-inspiring, 505 litres.
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.
For $260,000 there is a lot to get through, as there is on the less sporty A8. Start with huge 21-inch alloys, 17-speaker Bang & Olufsen stereo, panoramic sunroof, matrix LED headlights with laser lights, soft-close doors, acoustic glazing, leather trim, S front seats, extra leather over the A8, Alcantara headlining, carbon inlays, four-zone climate control, heated and cooled front seats, 'Virtual Cockpit' with S mode, and a tyre repair kit.
You also get active suspension, a sport version of the 'quattro' all-wheel drive system (with a sport differential), and a walloping great twin-turbo V8 to get you moving.
A massive touchscreen on the centre stack (familiar in Q8, A7 and Q7) hosts Audi's 'MMI plus' system, which is very good and does away with the console-mounted rotary controller. It also has wireless Apple CarPlay to go with the console-bin wireless charging pad. Android Auto is still USB. 'Audi Connect plus', now in full-featured glory, is also along for the ride.
Another technical highlight is the active noise cancelling which is meant to reduce the noise in the cabin the same way noise cancelling headphones do.
There's a clever rear seat remote control, which is a little detachable tablet to allow those who are being chauffered to faff around with various settings.
Our car had the $13,900 'Sensory Package', which adds a 1820-watt B&O 3D sound system with 23 speakers, electrically adjustable outer rear seats along with heating, cooling and massage function, and full leather.
We're talking a $254,900 entry price for the M4 CS, which – despite my attempts at justification – is a lot. Remember, the regular M4 is $168,700, and the M4 Competition is $186,500, so we're talking a sizeable premium here.
BMW justifies that price increase in two ways. The first is scarcity, with the M4 CS limited to just 50 examples in Australia. And the second is by dialling up every aspect of the M4's performance to terrifying levels.
The engine outputs are up, the weight is 20kg down, there are better brakes, better seats, a louder exhaust, a stiffer chassis – it goes on and on.
We'll get to some of the performance stuff in a moment, but here's what else your money buys you with the M4 CS.
It starts outside with staggered alloys, 19-inch up front and 20-inch at the rear, wrapped in track-ready rubber. There's also hi-po 'M Compound' brakes with red calipers, lightweight carbon racing seats that are heated up front, an Alcantara-trimmed steering wheel, the 'M Carbon' exterior package with carbon bonnet and roof, adaptive 'M Suspension' and a titanium exhaust that howls like the winds of hell.
The less performance-focused stuff is similar enough to the other M4 models including a 12.3-inch centre screen with digital radio, Apple CarPlay and Android Auto, a second 14.9-inch screen that handles your driving data and a head-up display. There's also twin-zone climate control, Merino leather upholstery and ambient interior lighting.
But all of that is secondary, really. This is about performance, specifically of the brutal kind.
Under that long bonnet is a 4.0-litre twin-turbo V8 pumping out 420kW and a diesel-like 800Nm of torque.
That's a lot, even for this big bruiser. Obviously, being an Audi S-car, it has quattro all-wheel drive, which is fed by an eight-speed ZF automatic. Which is in everything now. Well, just about.
That huge torque figure is available between 2000rpm and 4500rpm while peak power arrives at 6000rpm. The 0-100km/h sprint is despatched in - gulp - 3.8 seconds.
As it's riding on the MLB platform, the mild hybrid system is a 48-volt set-up. A lithium-ion battery in the boot takes charge from the belt alternator/starter, which means the S8 can coast at higher speeds with the engine off and also cut out at 22km/h and under in traffic.
The system can also add up to 60Nm of torque in the right conditions for up to six seconds, and if it happened for me, I didn't notice it.
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'.
The 10.5L/100km official figure is, shall we say, optimistic. The launch drive was mostly highway so there's no real information to be gleaned from that, so we'll have to wait for real world fuel figures.
I'd say 12-13L/100km is achievable if you don't like having fun, in which case, the lesser A8 is probably for you.
Audi says the MHEV system saves 0.8L/100km with an early cut-out for the stop-start and the ability to coast on the highway for over half a minute at a time.
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.
Driving any of the cars in this segment is a rare treat, whether it's the 'entry level' diesel or this top of the heap sports sedan. My day with the S8 was filled with the usual surprise and delight that only these tech-packed cars can deliver.
Heading out of the Sydney CBD in 'Comfort' mode, the car scans the road ahead and adjusts the active suspension accordingly. You already know it has active suspension because when you pull the door handle, the car lifts by 50mm to make it a bit easier to get in.
The suspension's party trick is flat-topped speed bumps - drive at one, brake a little and sense the way the body feels like it stays exactly where it is in the air but the suspension almost completely flattens the speed hump.
It's uncanny and almost unnatural, with just the tiniest change in altitude and no noise from the suspension.
It also manages the terrible narrow lanes of CBD thoroughfares with ease, the lane keep system letting you know if you're straying.
On to the motorway and you get a feel for its crushing performance. You won't hear much, though - the stereo's noise-cancelling system shuts out almost all tyre noise and consistent wind noise is largely banished, too.
I'm going to admit I gasped when I found some corners. Active suspension bodes well for the tricky stuff, as does the all-wheel steering. Both are exceptionally clever systems for making the car feel a lot smaller in town and in car parks but they're also really good if you want some fun.
But the way the rear-wheel steer adds agility to such a big car is hilarious and clever. While you can't quite chuck it around - and really, you're not buying an A8-sized car for that kind of nonsense - brisk progress is far from intimidating.
Now, obviously, a Ford Fiesta would drive away from the S8 in the really tight stuff but it would take some time to properly shake it. The colossal torque from the V8 hurls even this two-tonne-plus limo out of the corners in a most satisfactory manner.
It's surprisingly agile for a machine more than five metres long and two metres wide. If your passengers are corner enthusiasts, you'll all be having fun in near silence. It's oddly engaging to be moving at pace in such a hushed cabin.
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.
The S8's considerable safety equipment list includes nine airbags, ABS, stability and traction controls, forward AEB (up to 250km/h), reverse cross-traffic alert, lane departure warning, various collision mitigation and protection systems, exit warning, lane keep assist, active cruise control and on, and on, and on.
The rear seat's centre airbag is terribly clever, popping up between passengers to stop you knocking heads. Another clever trick is the way the car detects a side impact is about to happen, boosting the height of the side about to cop it to try and get the sills to take more of the impact, rather than the door.
Given the relatively niche status of the A8, let alone the S8, there is no ANCAP crash test or safety rating. One imagines given the ton of safety gear a five star rating is all but assured. Even the US IIHS gave the A8 a miss.
Expect no ANCAP rating here, I'm afraid. But the BMW 4 Series does wear a five-star rating from 2019.
The M4 CS gets six airbags (driver and passenger, side airbags, head airbags), along with what BMW calls its 'Driving Assistant Professional', which bundles active cruise control (with stop and go function), front and rear cross-traffic warning, 'Steering & Lane Control' and 'Lane Keeping with Side Collision Warning'.