Sometimes, putting a twin test together isn't straightforward. A new car arrives and there aren't any obvious rivals, so you end up having to be inventive. This leads to angry comments that, for instance, you're mad for pitting a Rolls-Royce Cullinan against a breezeblock on the pretence that they have similar silhouettes. [Note to self: they do, so organise that one]. This test was a tricky one. The new Audi S8 has arrived, but it doesn't have a direct rival. Jaguar stopped making the XJ in 2019, so the XJR is dead. And there isn't a Mercedes-AMG S63 as I write, because Mercedes hasn't got around to making one yet. Although it will do, soon. BMW has its 750i xDrive, of course, but there were two issues that precluded it: firstly, it isn't a designated sports model in the way that the S8 is - it doesn't have an 'M' in its name - and, even more crucially, BMW doesn't have one on its press fleet. So that's out, too.
However, it has only just stopped making the M760i xDrive, and, as you can see, that does have an 'M' its name. It was also a fabulous car. When it was launched back in 2017, I drove an M760i from Geneva to London and it proved to be a wonderful trip - the kind that reunites you with the love of cars. And bearing in mind the lovely M74 V12 has now exited stage left, outside of Rolls-Royces, why not celebrate its final act in a BMW under the pretense of old against new? Makes sense, doesn't it? Especially when you can buy this well-equipped M760i xDrive that was loaned to us by the Runnymede Motor Company for £73,000. That's a mere snip: £29,000 under the S8's starting price and nearly £60,000 less than it cost new. So this is the test: two all-wheel-drive luxury saloons, both with around 600hp that'll propel you to the 62mph benchmark in under four seconds. Which is better and why? Simple.
It's weird settling into the M760i after a few years away. It feels faintly classic already. It has digital dials, but these aren't configurable like the S8's, and the iDrive screen doesn't have the clarity of the pin-sharp TFTs in its rival, either. Plus it's decidedly analogue for a top-flight luxury car these days. It has buttons everywhere. Is this a bad thing? No, not in the least. It reminds me instantly that buttons are very useful: perfect for turning functions on and off quickly and easily. The S8, of course, looks more impressive with all its screens glowing prettily, and everything is touch-sensitive and minimalist - even down to the heater vents, which are turned off by electronic sliders instead of little wheels, as in the M760i. Let's call that progress.
That said, there are a touch-sliders in the M760i. These control one of the best 'gadgets' known to man - the ability to control temperature blend out of the face-level vents. If you haven't a clue what I am on about, BMWs have had this feature for years and it's brilliant. In most cars, you select a temperature for the climate control - say 20 degrees - and if it's colder outside the car will blow warm air until the system hits its mark. At which point you'll get a blast of cold air. Then, if you crank up the temperature a notch, you get more warm air until it hits that mark. This process carries on until you're baking in the heat of the Sahara Desert, but still with a biting north-easterly wind freezing your cheeks. Not in the M760i, though. If there's a chilly draft, leave the system on it ambient of 20 and simply adjust the face-vent slider up a notch to feel a warm summer's breeze. It's such a little thing, but to me it's worth a lot.
Both cars are beautifully made, though. They feel stouter than a pint of Guinness and lined with plush leather and a side helping of Alcantara - for the headlining. And some shiny bits. Which is where the S8 bites back, because its metal bits are actual metal. In the M760i, there's a much better chance those shiny bits will be sprayed plastic, which lets the side down a tad. Still, despite this it manages to look more homely. It's a softer, warmer and a friendlier environment than the S8, and there's even something of the art deco movement about the BMW's interior lights. I've always rather liked this little touch. The Audi is sharper, more angular and, for me, rather austere.
That doesn't stop it being just as comfortable and well appointed, though. As with the M760i it has sumptuous heated and ventilated seats, each with an array of massage functions that will knead you like dough, so you rise refreshed and happy at the end of your trip. The M760i's driver's seat is less contoured, and even though you can pump up its bolsters it doesn't grip you like the S8's. It's a bit like a giant, made-to-measure baseball glove that holds you securely. In every other respect, both cars are wonderful places to be. Their driving positions are impossible to fault: adjustable to the nth degree and with heated armrests positioned perfectly either side of you. It helps every journey melt away.
What about in the rear? After all, this is where these plutocratic pieces of automotive excellence are meant to excel. Well, both cars have all the technology you might want back there. A screen for the rear climate control, a screen in the centre - which pops out so you can use it as a tablet in the M760i - and screens jutting out of the front seats, too. The S8 has a slightly better default seating position; you sit slightly lower and less tiered behind the front-seat occupants. You're a bit perched in M760i's individual armchairs, which is presumably to accommodate the myriad motors beneath that, as with the S8, will recline you into all sorts of relaxing positions. The difference is the M760i came with a long wheelbase as standard, so it has a good 160mm more leg room than the S8, which is SWB only (though you can have a LWB A8). It also offers a more first-class experience, with a fixed central divider rather than a fold-down armrest in the middle. There's even a footrest that pops out the back of the front-passenger seat and illuminated vanity mirrors that spring down from the roof.
Does the sense of luxury extend to their road manners? If you're imagining each will drag its door handles, like lumbering knuckles, on the kerb stones of every corner, they don't. In fact, quite unexpectedly, the new S8 drives like a proper, old-school performance car. For a start, it has a 4.0-litre V8. This burbles away in the background or bellows soulfully when you bear down hard on the throttle. And while it lacks a third of the cylinders that the M760i has, it lacks nothing in straight-line speed - its pick-up most definitely matches its thundering noise. The Audi really wallops you into the seat, and feels relentless as it races through every gear of the eight-speed auto - although, when you're ambling around there's a bit more torque drop-off as it changes through the lower gears.
There's no apparent shortfall in grip, though. Adhesion through corners seems inexhaustible on the road, making you appreciate why the bolsters are so big: you need them to counter the cornering forces. Impressively, it doesn't feel big and blunt. It steers swiftly and accurately, and there's heft to its helm. You really can barrel into turns with a quick flick and trust it'll head where you're aiming. There even seems to be a sense that the chassis is vectoring the drive under its assured braking, because when you're stopping and turning at the same time, the nose seems to dart towards the apex more keenly; it's like a big pig that's just snuffled a truffle. It feels taut for such a huge car, too. It has selectable drive modes, of course, but the bandwidth between Comfort+ and Dynamic is conspicuously narrow, so even in its softest setting the S8 is biased towards agile. It doesn't roll alarmingly, and nor does it float. It's always poised, ready for action.
For much of the time, this is a likeable facet. But it does create an issue. Even at the softer end of its spectrum it feels relatively firm. Don't get me wrong, it's comfortable compared with most cars, with the ability to soften the worst abrasions; it's just a bit punchier than is ideal on those occasions when you want it to disappear silently into the background of a long drive. In these moments you tend to notice it picking up on ripples - and the moment you notice, it makes it seem restless. Then there's the refinement. A8s are known to be one of the best-insulated cars at speed. This is still evident in the S8's overall lack of noise, but with bigger tyres it inevitably generates more rumble than the variants lower in the range pecking order.
The M760i isn't silent, either. Here, the bulk of the noise percolating through seems to be via the glasshouse - there's a bit more turbulent flutter from the door mirrors and you're more aware of the rumble of other cars and trucks passing by outside. The M760i's own interactions with the road surface are well stifled, though. Well, audibly at least. There's more buzz coming up through the column than there is in the S8 - an issue that I've noticed in Rolls-Royces, too. And yet, between 50 and 70mph, this car switches on a mode that the S8 hasn't got in its repertoire: waft mode. Of course, you're suspended on air springs in both cars, but the M760i's appear to be filled with helium because the body has a freer and easier interaction with the road beneath. This detaches you more completely from most of the furrows that would otherwise spoil you day. It's only sharper stuff that catches it out, causing a thud - but the same is true of the S8 as well.
The steering is much lighter, too, so your first thought is it's vague and aloof. Except it isn't. It might not have much weight to start with, but it loads up well enough to gauge the inputs required and without thinking about them during or after the event. If anything, it's better than the S8's steering either side of dead centre. What you thought would be a Thames barge on back roads is actually a bobsleigh that you can funnel down lanes at one hell of a lick. The body control is no less adept than the steering. We're still in waft mode, remember, not Sport. It's still doing the cosseting thing, while somehow managing to hang onto itself over Oxfordshire's many crests. Put it this way: it never feels like an effort to hang onto the taillights of the pacesetting S8. There is a Sport mode, which, unlike the Audi's Dynamic equivalent, effects a real change of tone. It firms up the dampers by a noticeable amount and, while it's not punishing, it is a bit unnecessary. Even the brake pedal manages to disguise its effectiveness. It's softer and has more travel than the S8's, but this doesn't scupper your ability to shave off speed smoothly and with confidence.
Is it worth mentioning the M760i's playfulness? Probably not, bearing in mind it's a long-wheelbase limousine, but still. Now, this wasn't discovered on this occasion; when you're borrowing an expensive used car from a dealer kind enough to trust you with its stock, it isn't fair to go wanging around. But I did back in 2017, when I was on private ground with BMW's press car. And that wanged a lot, wagging its tail like a very happy dog. There was no sense that the S8 has that kind of flippant side - it's predictably serious about the business of going straight.
I haven't mentioned the N74 V12 engine yet. That's because I thought I'd save the best for last. Because as great as the S8's V8 is - and it is a rich and soulful thing - as Nic Cackett said, "it isn't a V12, is it." A simple observation but a pertinent one. There's something majestic about a V12 that sets it apart from lesser engines - and I include monotone W12s in that observation. This is evident from the moment you turn the key, with the even whir of the starter, through to the smooth way they rev. It's a thing of feelsome beauty, and, well, sadness I suppose, as they pass, one by one, into the history books.
Effortless is a bit of a cliché, but how else do you describe an engine with 6.6-litres, two discreetly acting turbos and 590lb ft of twist from 1,500rpm (the same peak amount as the S8, but over 500rpm lower down)? Thesaurus.com suggests 'duck soup' as an alternative? Hmm. I'll just stick with effortless for now. And exquisite. And epic, for a bit of alliteration, and because it's all those things. It speaks to the engineer in me. It's deeply, deeply satisfying to listen to and imagine all the internals reciprocating and turning, and yet, when you open the bonnet and rest your hand on the engine cover: nothing. It's idling perfectly still, with only the clicking of its twelve injectors to tell you it's running. And despite what you might imagine, it was averaging 26mpg on the journey back down the M4 - about what you can expect from the S8.
And with that, you've probably guessed that of the two, I'd choose the M760i. The engine is a big part of it, for sure, but not everything. I also really enjoy its breadth of ability. The way it can be a soft and squidgy luxury car one minute, then surprise you with its tremendous agility the next. And I like that it has pretty much every toy that the S8 has, but you can use most of them by pressing a switch or scrolling through a list with the still-brilliant iDrive controller. Change is inevitable, but improved functionality isn't.
I do like the new S8, though. I think it looks the smarter of the two, with handsome side profile that's less, well, Albanian mafia than the M760i's. It's also beautifully made and, as a large performance saloon, crazily good. I wasn't expecting 2,295kg to go, stop and turn as well as it does. It is certainly the best version of Audi's long-running flagship - which is handy, because it will almost certainly be the last to feature a V8. But it is still two-dimensional when held up to the M760i, which corners as well as it cossets. The S8 is like a big RS6, which is mightier praise than it's ever been afforded before - but it can't quite manage to be a money-no-object limo at the same time. The M760i xDrive can, and that's why it wins.
Specification | 2022 Audi S8 quattro
Engine: 3,996cc, V8, twin-turbo
Transmission: 8-speed auto, four-wheel drive
Power (hp): 571 @ 6,000rpm
Torque (lb ft): 590 @2,050-4,500rpm
0-62mph: 3.8 seconds
Top speed: 155mph
Weight: 2,295kg
MPG: 24.6 (WLTP)
CO2: 260g/km (WLTP)
Price: £102,730 (£ 117,540 as tested)
Specification | 2019 BMW M760i xDrive
Engine: 6,592cc, V12, twin-turbo
Transmission: 8-speed auto, four-wheel drive
Power (hp): 610 @ 5,250-6,000rpm;
Torque (lb ft): 590 @1,500-5,000rpm
0-62mph: 3.7 seconds
Top speed: 155mph
Weight: 2,180kg
MPG: 22.0 (WLTP)
CO2: 294g/km (WLTP)
Price new: £132,310 (£73,000 used)
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