We like
Talon-like traction, sharp price, time-travel pace, sporty but comfortable ride, flawless ZF transmission

Room for improvement
Expensive options, fiddly drive settings, fussy steering when cruising

BMW is the champion of niches within niches but as BMW Group Australia's managing director Marc Werner says, the company will not build a car unless a customer asks for it.

Clearly then, customers previously have asked for the curious big-bummed 3 Series GT and 5 Series GT, the two-seater Mini Coupe and a jacked-up version of the 4 Series dubbed the X4 to name just a few of the company's left-field vehicles.

And now there are these: the X5 M and X6 M, BMW's most powerful all-wheel drives to date.

The power-pair have serious grunt – 423kW and 750Nm – from a torque-boosted version of the M5/M6’s twin-turbo 4.4-litre V8.

Because the dual-clutch transmission of the M5/M6 cannot cope with the extra torque of the pumped engine in the big SUVs, the latter get a conventional eight-speed torque-converter automatic transmission.

The union of forced-induction V8 M-power with masterful ZF engineering and xDrive all-paw grip takes the pair of SUVs to a new realm.

The X5 M makes a premium first impression. Climbing into the supportive M-Sport seats and assessing the well laid out interior reveals typical BMW restraint and taste but widespread use of leather and optional carbon-fibre.

We liked the versatile adjustment especially the side-bolsters that squeeze even the slenderest flanks – essential for taking on Tasmania's winding rural roads.

Finding the right driving position was easy and enhanced by the excellent M-sport steering wheel which, while fat in the hand was ergonomically perfect for a long thrash.

Fine-grade leather covers almost every surface of the interior, but for an additional $7800, your car will come with Merino leather – not the sheep – covering every surface. An expensive opulence for little gain maybe.

Traveling long stretches of road was effortless thanks to the well-appointed cabin, a ride that was sporty but never excessively firm, and the elevated ride-height, which allowed a better view of the stunning Tasmanian scenery.

Making small corrections to the steering while on straight freeway sections was a little fussy requiring unusual effort for only minor movement – perhaps as a result of the fuel saving function which reduces steering assistance when cruising.

The coupe-syle X6 M has noticeably less head-room, especially in the second row of seats, but it did not offend our 188cm driver.

We preferred the cosier cabin with irresistibly tactile alcantara roof-lining – another option costing $1700 or included with the leather pack.

But to dwell too long on the cruising ability of any M-badged vehicle is missing the point. When the ConnectedDrive navigation map showed the roads turning wiggly, the potent pair came alive.

Give or take 10kg, the X5 M and X6 M weigh 2200kg – a lot to drag around – but BMW has done a staggering job of mitigating the undesirable traits of mass, starting with that monstrous V8.

By putting its brace of turbos in the valley rather than outside each cylinder bank and taking exhaust pulses from both sides of the engine (CrossBank), BMW has all but eliminated turbo-lag.

The V8 develops its savage power in the most versatile way. Torque peaks at 2200 rpm but persists through to 5000 rpm, allowing effortless negotiation of hills, but the low-down grunt can lull the driver into short-shifting, however, by keeping the boot in, the devastating peak power takes over between 6000 and 6500 rpm.

The result is fearsome acceleration at any speed accompanied by an enthralling note.

Where the M3, M4, M5 and M6 all pipe some engine sound through the stereo system, BMW says the pair of X cars don't, instead opting for a more carefully developed exhaust system for a more honest soundtrack.

While following other cars in our convoy, we had an opportunity to experience the real exhaust note from the outside. It is loud, exciting and pure-bred M.

All that force is meaningless without an adequate transmission, and ZF's eight-speed auto is another point of excellence, with perfect ratios that tighten in the upper gears and shift speeds to match a double-clutch solution.

The auto also mimics a DCT by not creeping forward when the brake pedal is released, but when moving the transmission obeys instructions from the steering wheel paddles rapidly with aggressive upshifts and slick downshifts depending on the setting.

We liked the most aggressive mode which produced an almost anti-social crackle from the quad exhausts but perfectly matched engine to road speed when changing down for a heel-and-toe sensation.

The final part in the drivetrain is BMW's fire-and-forget four-wheel drive transmission.

Most BMW X5 and X6 owners would be happy to admit they have no intention of hitting any terrain more adventurous than a boat-ramp, so while the xDrive four-wheel drive system rarely walks mud and rock, BMW has seen an opportunity for on-road traction.

While the typical SUV does not lend itself easily to high-performance driving, this all-paw drive does. The ability to get abundant torque to the road is one of the X5 M/X6 M's most impressive qualities.

On ever changing surfaces, the power is shared around each wheel imperceptibly, allowing early acceleration out of corners with little indication of either under- or over-steer.

The 70 per cent bias of power to the back end maintains the typical BMW handling style but during heavy-handed maneuvers – when a rear-drive M-car would wind back the power – the X-cars simply send a bit more up-front and power on.

Driving a high-powered two-wheel drive vehicle on unforgiving surfaces can be exhausting requiring maximum concentration to prevent stability systems stepping in, but thanks to xDrive, the X5 M and X6 M was addictively easy to pilot with pace.

It has power and the ability to transmit it to the ground but the Munich M-mechanics have created a chassis masterpiece to complete a truly accomplished package with the X-M duo.

With a hulking mass riding higher than a car, frustrating body-roll is all too common in performance-focused SUVs but BMW's DynamicDrive uses ingenious anti-roll bars that use a motor to counter cornering forces.

Combined with self-leveling rear air suspension, 50 per cent bigger brakes grabbed by six-pot callipers and the largest wheels factory-fitted to any BMW, the X5 M and X6 M are surprisingly sharp through tight corners.

The variable-rate steering changes ratio as more steering input is applied, and we rarely crossed arms even in the tightest alpine twists. Generally, the steering gave good feedback at speed – a marked improvement over previous X-cars.

Body control is exemplary with no perceptible roll no matter how hard we pushed and, while the significant kerb-weight manifested itself in the tightest spots, it was always impressive and confidence inspiring.

Technically, the pair are very advanced, but things get a little too complex when it comes to the various switchable drive-modes.

Traction control has three settings, as does the engine, steering and transmission, while the dampers have two settings – a total of 162 different combinations to work through to find the perfect set-up.

We liked the two steering wheel-mounted M-buttons that access the driver's pre-programmed favourite selection. Perhaps three M-button options would have allowed the removal of all the other various switches.

If only BMW could have taken a simpler approach, like it did with the xDrive system with its one setting – point and fire.

Shuffling through the various combinations is time consuming, with only minor differences noticeable between each mode. Pursuing that ephemeral perfect combination would take an eternity.

We say set the suspension to comfort, engine and steering to sports plus, gearbox to most aggressive and ESC to M Dynamic and that will do for most driving situations. That said, the X5 M and X6 M is great in any setting.

The recipe of brutal power, technically spectacular transmission, clever four-wheel drive system and advanced chassis technology provides a vehicle that seems to defy physics, and we couldn't believe how efficiently we completed our lap of Tassie.

By efficient we mean time. BMW says the pair will use 11.1 litres of fuel per 100km but for the record our car managed a figure of 19.7L/100km. We state the figure more for bragging rights than useful consumer advice. You don't get something for nothing.

No doubt Mercedes will price its imminent ML-succeeding GLE AMG to do battle with the BMW X5 M, and its coupe version will be the first true rival to the X6 M, but beyond that there is nothing to compare with the BMWs.

Range Rover will sell you its supercharged V8 Sport SVR for $218,500 and the Porsche Cayenne Turbo S is a whopping $98,800 more than the X5 M at $284,700 but there is a less obvious rival within BMW's own ranks.

The infamous M5 super-sedan might not seem like a competitor, but the X5 M and X6 M will get to 100km/h in the same time, deliver 50Nm more torque, the same power, more grip, handling you could only differentiate on a track and room for a weekend away with the family.

Critically though, the X5 M will do all of that while saving a difficult-to-ignore $44,030 – or $35,230 if you opt for the X6 M.

So here is the bottom line. If you want the best value from a hyper SUV, buy the X5 M. If you want the looks of a coupe, Nurburgring performance and live at the end of a muddy track, buy the X6 M. And if you are thinking about buying an M5 you should seriously consider either.

Few people need an SUV and even fewer need to crack 280km/h, but with almost boundless all-day performance, five-seats and a big boot, BMW's pointless X5 M and X6 M starts to make sense.