Mercedes-Benz C63 vs BMW XM

What's the difference?

The Mercedes-AMG C 63 S Aero Edition is an absolute beast of a car, but it comes at a pretty hefty price. Yes you get a lot of performance, and the fact there are only 63 examples being made for Australia and New Zealand could be enough to get you to sign on the line. For me, though, if I was after a C 63, it’d have to be a wagon. It doesn’t need an Aero pack to look better.

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.

I’ve never been the biggest fan of the current C-Class Coupe’s styling. To me, it has always looked a little droopy, a little melted at the back. 

I have to say, the Aero Edition has changed my opinion somewhat, as the new graphic elements help lift it up a bit, visually raising its rear up like a stretching cat, tail in the air. I’m still not 100 per cent on it, but to my eye it’s better.

The carbon-fibre trim elements that have been added to the exterior certainly add some menace to the look, too, and I simply can’t help but constantly notice out of the corner of my eye the AMG pressing in the staggered, dished rims. At a glimpse, from a distance,  it looks like rim damage, but thankfully it’s not!

The staggered set-up does really add some width and mongrel to the look, as if it needed more, with its open maw lower bumper air dam, and the signature 'Panamericana' grille treatment which looks like an evil character out of a movie. If you know the one I’m talking about, let me know in the comments.

As much as the look matters when it’s parked in your driveway, it’s the cabin that arguably matters more, right? That’s where you spend your time, after all. Check out the interior images to see if you think it lives up to the exterior look.

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.

No two-door coupe is going to offer you the space and comfort of a sedan or wagon, that’s just a fact. But that only matters if you plan to actually use the rear seats. If you don’t, then the Coupe version of the C 63 S might be perfect for you.

Even so, I managed to (only just) squeeze myself between the seat and the door opening to slide into the rear row. This won’t be easily achieved by all attempters, especially on the driver’s side.

Let’s just say I probably looked like I was doing something very weird to the driver’s seat as I spider-manned my way in. 

The rear space is tight for someone my height (182cm/6’0”) behind their own driving position, with knees hard-up against the seat in front and not much headroom (my noggin’ was brushing the ceiling) or toe space (size 12s don’t fit so well) to speak of.

It’s certainly a selfish car. Or maybe it’d be fine for smaller kids. There are two spaces in the back, both with ISOFIX child seat anchors and top-tether points.

But there is storage in the back - cupholders and storage caddies either side of the seats, though the storage situation improves in the front zone, with bottle holders in the doors, cupholders between the seats, loose item storage under the media screen and a covered centre armrest bin, too.

The front cabin is a special looking place, with carbon-fibre abounding across the dash and nice trim on the doors. The AMG steering wheel is a sight to behold - it’s a flat-bottomed unit with carbon-fibre and Dinamica (that’s Benz talk for microsuede) trim: perfect for sapping sweat as you manhandle the C63 through the bends.

The seats are AMG Performance sports units up front, and the trim used is reserved for this model specifically: Nappa leather with yellow stripes. There are yellow details elsewhere, including on the rear seats, centre console and dash, and it certainly adds some visual excitement.

Media is controlled by a 10.25-inch display and Mercedes-Benz’s touchpad control system, but there is no touchscreen - rendering the Apple CarPlay and Android Auto smartphone mirroring technology somewhat tedious.

I’ve always had a gripe with screens that don’t allow touch but feature the tech that’s designed to transfer your phone’s screen to the media unit, and I can tell you the longer you spend twiddling the dial to get where you want to go, the more annoying it becomes.

The Burmester sound system has 13 speakers and is rather good, but I prefer the sound from the standard fit variable sports exhaust. So maybe that quibble with CarPlay isn’t that big a deal.

And if you just want to charge your phone, and there’s a second USB port up front, as well. Note: in non-Aero Edition C 63 models without the carbon-fibre interior pack, you also get Qi wireless phone charging, but it’s deleted from this variant and any model with the carbon pack.

The driver has a 12.3-inch digital info display to show where you are and what the car is up to, and there’s a head-up display as well. Yep, there’s standard sat nav with live traffic updates (and even live fuel price updates) - it’s just a shame the maps still look early 2000s-spec in 2D layout.

Cargo space is okay. The claimed cargo capacity or boot volume is 355 litres (VDA) with the rear seats in place. That’s small for a coupe of this size, and the shape of the boot (with a hump behind the rear seat) isn’t great as things do move around quite a bit.

But, thankfully, Mercedes has included its clever foldable storage box system under the boot floor - it goes where you might usually expect a spare wheel, but there isn’t one in this car. Instead you get Mercedes’ 'Tirefit' repair kit with an electric pump.

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.

Open the shapely bonnet of the C 63 S and you’ll find a hand-assembled horsepower-monster engine with a printed name plaque to prove it.

The 4.0-litre twin-turbo V8 produces 375kW of power at 6250rpm, and 700Nm of torque from 2000-4500rpm. It runs a standard-fit nine-speed 'Speedshift MCT' (multi-clutch transmission) automatic, and it’s rear-wheel drive. And yes, that means it likes to boogie.

The claimed 0-100km/h time is just 3.9 seconds, and top speed is apparently pegged at 250km/h. Yeesh.

The name on the “Handcrafted by” plaque on this particular engine? Hat tip to you, Julian Rembold. This is quite a piece of work. 

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.

High numbers are what AMGs are about. Sadly that’s the case not only for performance outputs but also fuel consumption.

The official combined cycle fuel use claim for the C 63 S Coupe is 10.3 litres per 100 kilometres, and you need to fill it with 98RON premium unleaded fuel, too.

On test? Well, across a mix of different driving - urban, highway, back road and spirited stints - I saw an 'at the pump' return of 12.2L/100km, while the digital readout stated 12.0L/100km.

Given the performance on offer, and how much I took advantage of it during my week with the car, that’s not bad…

Fuel tank capacity is 66 litres. So go easy if you know there won’t be a fuel stop for a while.

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.

Just one word sprang to my mind when it comes to accurately describing the performance on offer from this car. The word is ‘brutal’.

Smash the accelerator and the power and torque on offer is enough to make your eyes feel like they’re not doing the right thing anymore. You get pushed back in your seat with a surge, and your ears are also rewarded with one of the best soundtracks in the automotive world. 

The engine builds pace with enormous intent, and the sound that comes from under the bonnet and out the back through the exhausts is addictive.

Yes, there is an active exhaust button which you have to press to make sure that you hear all that noise if you’re running around in 'Comfort' mode, and during my time with the car it was active the whole time.

I had some questions from neighbours over the week that I had this car about whether it was actually nice to live with on a day-to-day basis. And the answer is yes, if you put it in comfort mode it’s surprisingly amenable. 

The ride is really well sorted at pace despite having a bit of that trademark low-speed wobble that seems to afflict Mercedes products from A-Class through to the GLE SUV. But it wasn’t bad enough to really bother me, as most of my time was on highways and backroads.

The steering is direct and accurate. The only thing you need to be aware of is that you will lose traction at the rear axle when you put your foot down hard. And for the enthusiast that’s exactly what you want. 

I know I want to feel the thing squirm under throttle. It’s a rear-drive V8 coupe, after all. You want to feel like you’re a vein in its bicep muscle; you know, the one you see in a weightlifter’s arms – the one that wiggles around a lot. You want to have that. Right?

On the performance front it is exceptional. Twist the little dial on the wheel to 'Sport' or 'Sport+' (I didn’t sample 'Race' mode as I wasn’t at a racetrack), and everything feels like it’s had a protein shake.

Even so, in that mode it steers brilliantly, there's a nice feel through the wheel, and the ride, while stiff, controls the body brilliantly when you change directions. 

The transmission is very good, too. In Comfort mode it can take just a second or two at first to become accustomed to the idea that you want to drive aggressively.

But in Sport mode, or when you select the manual transmission mode using the trigger button on the steering wheel, you will certainly get the most out of the engine. That’s what I did when I was driving it in a ‘spirited’ manner.

If you are just after that high-end Coupe cruiser experience, it’s a relatively quiet car (provided the surface below isn’t the coarsest of coarse-chip bitumen), with enough luxuriousness to make it feel premium as well as sporty. That’s an important thing to consider, especially at this price point.

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.

Mercedes-Benz is among the minority of luxury brands now offering a five-year/unlimited kilometre warranty plan - most still have three-year cover. So that’s a tick.

And the service intervals are pegged at 12 months/20,000km. Another tick.

Plus you can either pre-pay your service plan in three-year ($3800), four-year ($6000) or five-year ($6550) plans - roll it into the finance package, and it won’t hurt quite as much.

According to Mercedes, the three-year coverage option makes for a $900 discount over pay-as-you-go servicing.

Roadside assistance covers the five-year new car warranty period, too. So Mercedes seemingly takes good care of its customers. But if you have any concerns or questions over reliability, problems, issues or complaints about the C 63, check out our AMG C 63 problems page.

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.