BMW X5 M VS Mercedes-AMG GLE63 S

Imagine, for a moment, if performance cars were athletes.

A Lotus Elise, for example, would be AFL wizard Cyril Rioli, light with superb agility, while a Porsche 911 GT3 would be Usain Bolt, lithe and unbeatable on-track. An HSV GTS? Perhaps NBA phenom Lebron James, large and powerful but surprisingly athletic.

So where does this analogy leave the likes of the BMW X5 M and Mercedes-AMG GLE 63? Well, these hulking brutes are the automotive equivalent of Hafthór Júlíus Björnsson; the 206cm/190kg Icelandic giant who plays The Mountain in TV show Game of Thrones. This modern-day viking is one of the world’s strongest men, but if there was ever a World’s Strongest Car competition, the X5 M and GLE 63 would likely be facing off in the final.

They might have started life as humble city-dwelling off-roaders, but thanks to the attentions of the mad minions at M Division and AMG, this pair has emerged as snarling beasts, capable of swallowing sportscars whole – or at least, so their makers claim.

Certainly their sprinting ability is world class. The new BMW X5 M musters 423kW/750Nm from its 4.4-litre twin-turbo V8, an increase of 15kW/70Nm over its predecessor, sent to all four wheels through an eight-speed ZF torque-converter automatic.

BMW claims this 2275kg monster can hit 100km/h in just 4.2sec – a claim it matches on the strip. Rudimentary launch control builds a few revs against the brakes, catapulting the Beemer off the line. There’s so much grunt that a short-shift to second doesn’t cost it any time and it hurtles over the quarter mile in a scarcely believable 12.38sec at 182.91km/h. 

Under full acceleration the nose rises like a speedboat, the most ferocious noise bellowing out of its AMG-branded quad tailpipes. The soundtrack is straight out of 1960s Detroit, with a crack like snapping timber on full-throttle upshifts – you could easily buy a GLE 63 for the noise alone. It’s not long for this world, the M157 engine, but years of development have made it smooth and supremely powerful – it’s the heart and soul of the car.

Two such words that can’t be applied to the BMW’s engine. Undoubtedly effective, it may be every bit as potent as the AMG powerplant but it has none of the character. It’s as if the engineers couldn’t figure out what they wanted it to sound like, so they made it sound like everything.

There are hints of diesel and highly tuned four-cylinder, a dollop of in-line six and very occasionally something that approaches a traditional V8. The thunderclaps from the exhaust on upshifts are a nice touch, though.

The transmission is similarly confused. M Division engineers have done a remarkable job in making the X5’s eight-speed auto mimic the behaviour of the seven-speed dual-clutch ’box found in other M cars, but it’s debatable whether there’s been any benefit in doing so.

The shifts are extremely quick, with only the occasional downshift refusal a giveaway it’s a regular auto, but its low-speed behaviour isn’t as smooth as it should be and the engineered-in thumps on full-throttle upshifts are uncomfortable and unnecessary, though some may enjoy the sense of theatre.

It is, however, leagues ahead of the Mercedes ’box. The seven-speed wet-clutch MCT auto feels a generation behind, though the latest C63 shows what it’s capable of. It’s smoother from rest than the BMW’s, but low-speed stumbles aren’t what you expect from a $190K car, and it’s slow to respond to shift requests via the paddles, if it responds at all.

For day-to-day use it’s best left to its own devices in Sport mode, but Sport+ is well calibrated to more spirited driving, holding gears to redline under acceleration and downshifting super-aggressively under brakes.

The resultant engine braking is an asset, as despite a double-wishbone front-end and multi-link rear the GLE 63 is no natural handler. You sit high in the driver’s seat and the centre of gravity feels higher still. Combine this with relatively soft suspension and the big Merc sways during hard cornering like a skyscraper in a hurricane. It’s no accident the ESP can’t be completely deactivated, though it might prevent a few.

The electronics are quick to intervene if you overstep the threshold, but work within the parameters and the softness makes the GLE quite entertaining to drive. It takes little effort to rotate the car on the brakes in slower corners and you’re always busy behind the wheel making inputs or corrections to keep everything pointed in roughly the right direction.

Push too hard, though, and it’ll start to misbehave. The steering, while well-weighted and linear, refuses to change under load, the brakes soften, and despite a 40:60 front/rear torque split, the inside-front wheel spins up on corner exit before the ESP dramatically kills momentum.

The GLE 63 essentially feels like a traditional four-wheel drive with a nuclear powerplant under the bonnet; that’s not to say it handles like a Land Rover – it can carry impressive speed in faster bends – but it quickly becomes clear that the best way to drive it is to coax it through corners before unleashing the engine and demolishing the straight bits in between.

It’s not helped by wearing Michelin Latitude Sports tyres, which while enormous (295/35 ZR21 all ’round) offer nothing like the grip of the X5 M’s Michelin Pilot Super Sports; the same tyres, incidentally, fitted to the M3 and Ferrari 488. Measuring 285/35 ZR21 up front and a whopping 325/30 ZR21 at the rear, the sticky Michelins give the BMW far higher lateral grip levels. To be fair, though, the rubber is merely making the most of a very talented chassis.

If you really want to know how good M Division’s engineers are, drive an X5 M. How they manage to make this 2275kg leviathan handle like an oversized hot hatch is remarkable, except no hot hatch feels this rear-driven, and only the likes of the Audi RS3 or Mercedes-AMG A45 could match the X5 M’s monstrous punch out of corners. The diff set-up is magic; nail the throttle early and it’ll briefly power oversteer, even in the dry, but more often than not power is quickly and efficiently shuffled to the wheel that needs it most.

MDM mode allows enough leeway to feel the car moving around and is probably best left engaged when dealing with this much weight and speed. As impressive as the BMW is, you can only fight physics for so long, and when the grip does run out there’s little you can do but wait, somewhat anxiously, for it to return. The X5 M, as with all these mega-fast SUVs, is just too heavy and generates too much momentum to allow you to adjust your line if you overcook it.

Few, however, will ever reach that limit. Most will be happy chasing down sportscars while the kids in the back giggle in delight (or scream in terror). The only real blot on the X5 M’s dynamic copybook is, sadly in typical BMW fashion these days, the steering. M Division has managed to CPR some life into the standard X5’s flatlining tiller, but none of the three steering settings feel right in terms of weighting, nor do any offer any real communication.

The BMW wins more points on a more prosaic level, though. It’s not a pretty car, with few visual cues as to its potency, but then there’s always the X6 M for those wanting to be noticed.

The interior is much more successful. There are lashings of leather and carbonfibre trim to remind you why you spent $185,900 on an SUV, acres of space, plenty of equipment – sunroof, 16-speaker Harmon Kardon stereo, digital TV, a raft of active safety gear – and iDrive offers a beautifully intuitive way of controlling the infotainment system.

Despite the shift in name from ML to GLE, Merc’s recent mid-size SUV update was more of a facelift than an overhaul and its interior lags behind the BMW and Audi competition.

Not so much in terms of equipment; like the BMW, there’s all the latest active safety kit, digital TV, a sunroof, ear-melting stereo and plenty of leather, but the multimedia screen is neither as big nor as integrated and the operating interface feels clumsy and unintuitive in comparison. You only have to ‘write’ a sat-nav instruction on a touch-pad once for turning a dial to seem old-fashioned.

It’s probably clear by now that the Merc comes second in this comparison. Straight-line pace aside, the GLE 63 is neither as capable nor as rewarding to drive as the X5 M, its interior doesn’t feel as special, it’s more expensive (before options, anyway) and less fuel efficient, though the BMW won’t be winning any ‘green car’ awards any time soon, either. But that’s also not the whole story, as it turns out this is a comparison between a flawed car that’s very likeable and an incredibly competent one that isn’t.

If you take into account how these cars are going to be driven the vast majority of the time – to the supermarket and on school runs – then the GLE63 is arguably the more enjoyable machine. It’s a modern interpretation of the traditional US muscle car; not overly fond of corners, it’s a bullet in a straight line and that engine will raise a smile leaving every traffic light.

Conversely, if you’re not driving like your hair’s on fire, the BMW is a little, well, dull. Admittedly, that is a highly subjective assessment – if the BMW’s understated looks and unusual engine note strike a chord then it’s a slam dunk, as it’s objectively the better car.

But we could equally understand why some will choose the AMG without hesitation. Think of it as the difference between the MVP and the fan favourite.