There’s something very traditional and actually quite reassuring about pitching one four-door, four-wheel drive German V8 against another four-door, four-wheel drive German V8. Neither 630hp, 4.0-litre Audi RS7 Performance nor 635hp, 4.4-litre BMW M5 CS are trying to be anything that they’re not; these aren’t 120kWh BEV behemoths claiming to save the world or SUVs pretending to be sports cars. They’re supersaloons, pure and simple (or close enough, in the RS7's case), here in what should be their ultimate, most persuasive formats. Enough is known about the M5 CS to understand its inclusion; the RS7 is aiming to go one better than the RS6 equivalent and surpass a BMW Club Sport adversary. 

Plus, well, the Performance is here to remind us all that the RS7 exists. It can seem like the forgotten sibling as the car world gets all tizzy about another RS6, which seems unfair given how much is shared. Sure, it doesn’t do practical performance quite so effortlessly as the RS6, and its design might not be as universally popular, but this is still a ginormous Audi capable of hauling lots of people and lots of stuff around with a swaggering twin-turbo V8 as accompaniment. It probably deserves more recognition than it gets - or at least something like parity with the RS6. 

Especially when it’s this good. If ever there was a car not to judge on appearances, the Performance is it. No doubt you’re seeing a two-tonne, five-metre-long, lightbar-equipped Audi RS on 22-inch wheels and reaching some conclusions already. One is rooted in experience perhaps, though certainly not applicable here. It rides well, for starters, this RS7, with proper plushness and a level of comfort that the M5 - with its measly, staggered set up of 20/21s, and more tyre sidewall - can’t quite match. 

At low speed it’s impossible not to brace for the impact from speed bumps and the like, only to be largely undisturbed; the BMW is tenser, tauter, less amenable. It means you can really lean into what feels like this Audi’s preferred state: menacingly cruising around, making a rude noise, going faster than is strictly necessary and feeling ever so slightly brilliant about it. Little does feel-good on four wheels like the perfectly executed ‘bahnstomer, even at a quarter of its top speed. 

Like the RS6 Performance, much of the RS7’s dexterity can likely be attributed to its unsprung weight savings. Vorsprung spec here brings those incredible Y-spoke 22s, which save 5kg each (!) compared to the standard wheel. With the optional (£9k) ceramics - a monster 440mm at the front, 370mm rear - added in also, another 34kg comes off the unsprung mass. So 54kg in total, a far-from-insignificant amount even on a heavy car. An RS7 Performance with non-lightweight rims and iron brakes surely wouldn’t ride with quite such aplomb. Optionally achieved or otherwise, it’s quite some party trick. 

Corners bring the Audi even more animatedly to life. The standard RS7 was always an able handler, as fast as anything across the ground, if fairly aloof with it. More often than not, it seemed more content with the driver as a spectator to all it was capable of rather than bringing them along to the party. That’s unwelcome, if familiar, trait has been turned on its head; taking eight kilos of sound deadening out has brought some V8 rumble to proceedings, the steering - if still a bit fast for a car of this size - offers some resistance to work against at last and the sport diff can really be felt gnawing at the tarmac to hurl you from a bend. It’s still missing the last few finer details in terms of feedback, but the Performance is a significant step in the right direction from the standard car. While, crucially, not sacrificing that crushing performance or undeniable usability.  

As is fast Audi lore - fast car lore generally now, really - the RS7 does admittedly need setting up to really demonstrate its best. The Dynamic setting for the suspension may well bring benefits on a track, yet on road it needlessly unsettles the ride after Auto, and the same setting for the drive system makes the throttle too abrupt. However, you’ll certainly want Pronounced for the sound to ensure maximum malevolence. And the sport diff at its most ferocious to claw everything out of the surface and the giant Continentals. 

Configured, thusly, the Performance is the RS7 as it always should have been. There’s everything here that fans of the standard car ought to appreciate, while those who really want to be a part of the action can enjoy an RS7 with a bit of grit and tenacity plumbed in. Much like the recent RS3 and RS4 Competition, a properly memorable fast Audi is most certainly welcome. It's just a shame they’ve arrived in such limited numbers and for so little time.

Still, it bodes well for whatever the future holds for Audi Sport. There are clearly folk there who care about the intangibles, so we’ll have to hope for their continued involvement once the V8 has gone. (The RS e-tron GT is an auspicious beginning.) This RS6 and RS7 could have been left untouched to see out their days with a decent legacy; that the Performances exist means they’ll both be remembered as properly great flagships. And much the same can be said of the BMW. The F90 M5 was a very good saloon without ever being truly unforgettable; its lasting status overly dependent on it being the last purely combustion version. It was never an M5 that left you yearning for another go, or dreamed of owning one day. It needed the sensational CS to move the game on. 

Granted - and not for nothing either - if the requirement for a car like this is merely otherworldly speed combined with soothing comfort, the Audi takes it. Despite the weight advantage on paper for the BMW, there’s not much in it in real life - that extra 74lb ft of torque for the RS7 pays dividends every time the throttle is pressed, even if the response is sharper in the CS. It’s arguably the more charismatic V8, too, boasting an old-school, low-pitched rumble alongside some turbo fizz - however strangled by filters - against the BMW’s more motorsporty blare. Be in no doubt: there's no situation where the Audi is being left behind.

That said, if we’re talking about sheer, unadulterated, tell-the-grandchildren experience, the CS is in a class of its own. As it is every time it faces any kind of comparison, really, against nearly any kind of car. Large, heavy saloons simply aren’t meant to be this absorbing, this tactile, this obscenely gratifying to hustle down a road. It’s a genuine privilege to experience it getting better and better the faster it's driven, safe in the knowledge nothing else manages its mass or changes direction like this. As the cracks begin to appear in the RS7’s facade - when the brake pedal isn’t so reassuring or the damping finally wants for precision - so the BMW is at its imperious best, unruffled and unflustered by nearly any challenge asked of it. Yet still delivering absolute clarity from its controls, the measured, ideally weighted steering an obvious highlight when sampled back-to-back - it isn’t merely fast to a fault. The CS is monstrously quick and supremely well-sorted. 

While it might not be quite so serene around town, it's tough to argue that as a priority in two cars so explicitly focused on driving thrills. With speed under its wheels, it’s the M5 that makes best on the promise of super saloon nirvana: it’s composed, communicative, confidence-inspiring and proper fun to boot, everything that could be desired from an M car and more. Thus far the only thing to deliver similar poise, balance and finesse is - you’ve guessed it - the smaller M3 CS. The transformation from smaller, lighter, rear-drive cars that couldn’t always keep a handle on themselves, to larger, heavier xDrivers that are more capable as well as more satisfying to drive really has been astonishing to witness. 

So it’s probably easy to guess which way the verdict goes on this one, without even factoring in the BMW’s superior driving environment or its more classically handsome look. Which isn’t to dismiss the RS7 Performance out of hand for a second. A possibly slightly fairer, like-for-like comparison with a standard M5 Competition or something like a Porsche Panamera Turbo would have been a really close-run thing, such are the gains made in driver involvement and sense of occasion over a standard ‘7. RS6 aside, this is the best Audi V8 in yonks, and, if maybe not the last hurrah epic that some might have been hoping for, it certainly provides plenty of evidence that Audi Sport can still turn in a laudable headliner. Every moment spent aboard was a satisfying one. 

But up against it in this case was a supersaloon that currently knows no equal. You drive the M5 CS not thinking of what’s so stunningly good, but rather what might possibly be changed for the better. Seldom do performance cars of any stripe feel so cohesive and so authentically rewarding, let alone tech-heavy large saloons with four-wheel drive. It was easy to dismiss the CS at launch, with its scant 70kg weight loss, seemingly inconsequential suspension changes and silly racecar-style lights; only now it’s the naysayers that look daft, because this is the ‘bahnstormer par excellence. As fast, entertaining, engaging, luxurious and loutish as you could ever want or need a flagship model like this to be. As fans of the genre, it’s impossible not to be smitten. The CS is a triumph, as good a purely V8 saloon as there will ever be - let’s hope BMW can continue this rich vein of form into the hybrid era.

SPECIFICATION | 2023 AUDI RS7 PERFORMANCE

Engine: 3,993cc, twin-turbo V8
Transmission: 8-speed torque converter automatic, all-wheel drive
Power (hp): 630@6,000rpm
Torque (lb ft): 627@2,300-4,500rpm
0-62mph: 3.4sec
Top speed: 174mph
Weight: 2,065kg (unladen weight without driver)
MPG: 22.8
CO2: 282g/km
Price: £125,495 (OTR price as standard; price as tested £136,495 comprised of RS Ceramic brakes with blue calipers for £9,000, RS Dynamic Pack Plus for £500 (189mph speed limit raise) and RS Sports Suspension Plus with Dynamic Ride Control for £1,300)

SPECIFICATION | 2022 BMW M5 CS

Engine: 4,395cc, V8, twin-turbocharged
Transmission: 8-speed auto, all-wheel drive
Power (hp): 635@6,000rpm
Torque (lb ft): 553@1,800-5,950rpm
0-62mph: 3.0 seconds
Top speed: 189mph
Weight: 1,825kg (DIN, without driver, 1,900kg EU)
MPG: 25-25.5
CO2: 253-258g/km
Price: £140,780