Audi S8 vs BMW XM

What's the difference?

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.

It’s pretty obvious the XM is designed to impress people with big wallets and an appetite for a techy experience that’s also not without a few green credentials. The ability to motor around as a fully-electric vehicle for up to 80km or so is a big plus and the electric-ballroom interior vibe is hard to ignore, as well.

But from our perspective, the full-fat, twin-turbo V8, while offering startling performance, is perhaps a lost opportunity to follow some of BMW’s competitors into the engine-downsizing space. Then again, when you floor the throttle and 2700kg hurtles forward like a big dog on a short chain, you can see where BMW is coming from.

Perhaps the biggest letdown is the ride quality – or lack of it. While it’s understandable BMW wanted the most dynamic version of the XM it could manage, the end result plays against the vehicle’s otherwise long suit of hyper-luxury. Doubtless, BMW would argue that to soften the chassis would have been to introduce a chink into a no-compromise product. But, perhaps, sometimes a sensible compromise is the way forward.

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.

There’s nothing subtle about the way the XM looks. It probably pulls up just short of brutalist (or maybe not) but even those who find its slabs and angles attractive have to admit that it’s bold.

The now-trademark giant nostrils set the mood and the rest of the exterior suggests some kind of armoured transport for presidents rather than wheels for the school run. Doubtless, this will hardly be seen as a fault by those in the market for such a thing.

The real surprise here is that the XM does not share a bodyshell with any other production BMW. Sure, the V8 petrol engine and wheelbase are common to other BMW and M models, but the sheet metal is the XM’s and the XM’s alone. That in itself, is quite a statement of intent.

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.

Given the vast exterior dimensions and a weighbridge ticket the wrong side of 2700kg, it may come as a surprise to learn that the XM is strictly a five-seater with not even an optional third row.

That said, the uber-SUV Lexus LX in flagship, Ultra Luxury, trim offers just four seats in deference to the VIP clientele it’s pitched at, but also comes complete with reclining rear seats and a passenger’s side footrest which the XM can’t match.

Staying in the rear seat, there’s lots of legroom and plenty of space under the front chairs for feet. A lot of that is down to the wheelbase the XM shares with the BMW X7, and even behind a tall driver, there’s lots of space. In fact, compared with a BMW X5, there’s a full 150mm of extra legroom.

The pew itself flows into the door trims for a lounge effect which looks great with the contrasting light-coloured trim, and the centre arm-rest folds down to reveal a pair of cupholders. Extra storage space can be found in fold-out pockets in the rear of each front seat which also house a small, lidded panel that opens to reveal USB ports and power sockets. Dual-zone climate controls are also part of the rear-seat experience.

The gee-whizz stuff hasn’t been ignored, either, and the prismatic roof lining is nothing if not a talking point. But would a panoramic sunroof have been of more value to many buyers? The ambient lighting is a nice touch, too.

Up front, the view is dominated by the giant, twin curved animated dashboards. They deliver information and lots of it, to the point where it can almost seem a bit overwhelming.

The head-up display helps simplify things, but there’s absolutely no doubt there’s a lot going on in this cabin. Again, this is modern luxury motoring, but it remains that the menu system will take time to learn, even if the touchscreen function gives you an option on how you control things.

Multi-adjustable front seats are part of the deal and there’s an M-spec steering wheel which is heated. And although it features plenty of buttons, isn’t as daunting perhaps as the multi-spoked equivalent in some high-end AMGs of late.

The stereo system is also worthy of a mention, being a Bowers & Wilkins unit with roof mounted speakers and no less than 1500 watts of power. Digital radio is part of the package.

Even though it doesn’t offer a seven-seat option, luggage space in the rear of the XM is hardly class-leading. Cargo volume with rear seat up is 527L and 1820L with it folded.

Much of the wheelbase is devoted to rear-seat stretching room and although the batteries for the electric motor are positioned under the rear seat, the floor of the cargo area seems quite high.

The XM is one of those 'no options' vehicles. That is, you pay the basic price, you get one with the lot. The aged leather and even the optional 23-inch wheels and tyres are no-cost options, so it’s clear where BMW is aiming the thing.

As well as the plug-in driveline, all-wheel drive and all the M driving focus, the XM features plenty of tech including massaging front seats, heated seats all around, a high-end stereo, heated and cooled cupholders, four-zone climate-control, wireless phone charging and twin, curved info screens for the driver measuring 12.3 and 14.9 inches. The novel roof lining also features 100 pin-point LEDs for effect.

The cost of such detailing is a not insubstantial $302,200. That figure does, however, undercut two of its main rivals, the Lamborghini Urus ($395,888) and the Aston Martin DBX ($356,512).

It’s also worth mentioning that the XM is not even BMW Australia’s most expensive model; in fact, it’s fourth on the ladder.

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.

Here’s where the XM starts to justify its price-tag. While the use of an electric motor to boost a petrol engine has allowed some manufacturers to reduce the capacity of the latter, no such restraint has been shown for the XM. Instead, it gets the full 4.4-litre, twice turbocharged V8 that we’ve come to know and love from this brand.

It’s not that this is the engine’s first date with hybrid technology, but the mild hybrids that have come before it can’t match the XM for sheer brutality when both power units are unleashed.

The petrol V8 can muster up 360kW and 650Nm which, when boosted by the electric motor, jumps to a total of 480kW (combined) and 800Nm.

While the petrol engine drives through an eight-speed torque-converter automatic, the electric motor also drives through the transmission, an arrangement that is a bit different to some hybrids which use the petrol engine for the rear axle and the electric motor to drive the front wheels.

Of course, the requirement for the XM to feature permanent all-wheel drive, regardless of what power unit is running at the time, forces this layout.

Speaking of all-wheel drive, The XM’s version of BMW’s 'xDrive' layout has been specifically tuned for this vehicle and includes torque vectoring as well as a limited-slip rear differential.

The system has the ability to vary the torque split front to rear, with the default rear-bias giving a more sporting feel on good surfaces. An active rear differential also helps give the car a rear-drive feel.

As well as modes for 'Hybrid', 'Electric' and 'eControl' modes, the XM sticks with the M tradition of offering two M buttons which can be configured to set the parameters for steering, driveline, chassis and, in the case of the hybrid XM, the degree of braking regeneration offered.

Four-wheel steering is also part of the XM’s repertoire and, interestingly, there’s no air suspension here; just conventional steel springs.

But it does feature an electrically-adjusted anti-roll bar system which aims to strike a happy medium between what the driver wants and the road conditions demand.

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.

A 25.7kWh lithium-ion battery provides the power for the electric drive. It’s mounted under the rear seat and can produce a purely electric range of between 82 and 88km (based on WLPT test protocols).

Charge time from a conventional wall-box is said to be about four hours but, interestingly, the XM has no provision for DC fast-charging.

Fuel consumption (combined cycle) is an EV-typical 2.7 litres per 100km, which equates to a low 61g/km of CO2.

Once you’ve depleted the battery on a highway journey, expect the petrol V8 to consumer somewhere between eight and nine litres per 100km at cruising speed.

Using EV mode means zero-emission operation but, as with any electric car, how the power is generated to recharge it determines its real-world green-ness.

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.

While any M car is supposed to be rapid and dynamic, it’s also true that the over-arching perception of big SUVs is that they’re comfortable and plush. None of which explains the ride in the XM.

Regardless of how you fiddle with the settings, the ride is always brittle. Those big tyres with their minimal sidewall somehow manage to find every crack and join in the road, and it’s these sharp-edged imperfections that thump through to the cabin the most vocally.

It’s enough to make you wonder who this car is going to appeal to. Will it take to race tracks? Almost certainly not. So the whole point of these suspension settings might be a bit lost on some people.

Performance, meanwhile, is insanely rapid for something that could pass as a bulk carrier. The biggest giveaway to the mass is the transmission’s earnest attempts to keep everything moving by feeling a bit hyperactive on downshifts.

Using the ratios is always going to be the strategy, but with all that torque, maybe it’d be nice sometimes for the trans to hang on to a taller gear and let the boost blow it towards the next corner.

The sound track? Polarising. Even if it doesn’t convince you that Hans Zimmer (who developed the various electronically-synthesised noises the XM makes) should stick to winning Oscars, the augmented sounds are background noise rather than the main event here.

Even the petrol V8’s naturally stirring backing vocals have been electronically tweaked with debatable results.

That said, it’s nice to have something to listen to that isn’t the insistent tyre roar which becomes even louder on coarse-chip surfaces.

Steering effort is light but there’s not a lot of feedback in terms of actual feel. In fact, it’s borderline detached and only the sheer speed of the rack confers any athleticism.

Also, the rear steering seems to come in a few milli-seconds after the front has started to turn. And for all that all-wheel-steering agility, this is never a car that shrinks around you.

As well as the usual passive safety features, the XM also hides the latest active safety gear. In fact, BMW reckons the XM has more driver assistance than any other M car before it.

Those elements start with the 'Driver Assistant Professional' which bundles active cruise-control with stop-go ability, steering and lane-keeping control, automatic speed limit assist and active navigation.

Parking assistance is also featured which incorporates a reversing assistance function, front, rear and panoramic camera views with a 3D view built in.

BMW’s 'ConnectedDrive' includes an emergency call function in the event of a crash or other emergency.

No ANCAP assessment so far.

Audi continues to fail to match Mercedes move to a five year warranty, sticking with three year/unlimited kilometre cover. BMW is still doing it too, so maybe Ingolstadt and Munich are playing chicken. 

You can get a five-year service plan for the S8, coming out at $3990 for the duration.

Like a lot of manufacturers, BMW knows consumers can be leery of EV tech when it comes to the cost of battery replacement. So, as well as the five-year/unlimited-kilometre warranty on the whole vehicle, there’s also eight years or 160,000km of cover for the high-voltage battery.

Servicing intervals are based on how the car has been used and it will inform the owner when a service is required.

A servicing package is included in the purchase price and BMW even throws in three years of roadside assistance.