We like
Gargantuan torque, responsive transmission, engine note, ‘Traction’ DSC setting

Room for improvement
Wind noise, ground clearance

The Pisa mountain range is an unforgiving place and, in the winter months, the asphalt is permanently hidden beneath a thick layer of ice.

Our drive began in freezing temperatures, at 1500 meters above sea level and in a metre of snow.

Simply approaching our test car on foot was treacherous, so it was comforting to know it had been fitted with Pirelli Scorpion snow tyres.

The X5’s interior is a comfortable place to be in normal conditions, but with the outside temperatures way below zero, the heated seats were particularly welcoming.

The tinted window glass cut out just enough of the snow glare so that sun-glasses weren’t necessary while on-board, and the full length sun-roof ($3700 extra) complimented the spacious feel of the cabin.

Our test car seated five with plenty of leg/head room and the 620 litres of boot space was adequate for any accompanying snow gear.

The interior is visually largely similar to other X5 models in the range, but the M50d gives constant reminder that it is a little bit different, with the famous M-badge marked behind the tachometer needle.

The iconic BMW ‘M’ isn’t just there for show though.

BMW don’t apply the coveted badge without good reason and the X5 M50d is no exception.

Under the bonnet is the same displacement 3.0-litre diesel engine as in the lesser xDrive 30d turbo and xDrive 40d twin-turbo variants, but the M50d has an additional third turbo.

Two small turbos provide boost from low rpm and the third larger turbo tops-up the charge pressure when the engine is up to speed.

The results are hose-stiffening boost pressures and a snow-blowing 740Nm of torque between 2000 and 3000 rpm.

All that torque could be easily wasted if an adequate transmission system wasn’t employed and this is where the BMW xDrive system comes in to play.

The system is simple at its core, using a tried and tested transfer-box as found in many 4WDs, but an incorporated clutch distributes the torque to front and rear axles.

In addition, the xDrive management system can also divide the power side-to-side.

In certain circumstances just one wheel can be driven rather than wasting energy and grip on spinning wheels.

On very slippery surfaces the system worked effectively and at no point did even heavy snow drifts provide a problem for traction.

The traction control system tried to intervene a little too readily in normal mode but when switched to ‘Traction’ mode the system allowed the snow tyres to slip a little, which is actually required for maximum grip.

BMW claims its system is the only one in the world which works proactively, predicting wheel spin before it actually happens rather than reactively after the wheel has started slipping.

It certainly felt like the huge torque was being well managed with a little oversteer permitted, but traction control would step-in if the back end stepped-out too far.

Once the snow and ice had cleared below the snow-line the unsealed roads presented a different hazard becoming wet and muddy.

In this environment the xDrive continued to operate as it had on the snow.

Power was sent to the wheels with the most grip allowing a decent pace to be maintained all the way down the mountain.

Despite the surprising lack of body-roll the X5 rode comfortably over uneven surfaces, with some noise transmitted in to the cabin but with no unsettling vibration.

This was particularly surprising given the X5 wore 20-inch wheels and very low profile tyres.

The mountain access road leads from the Snow Farm ski resort and was used for the Race to the Sky event that ran from 1998 to 2007.

The challenging route has tight hair-pin bends, fast straights and punishing gradients, but the X5 remained composed defying its considerable 2200kg weight.

The brakes scrubbed speed consistently and showed no signs of fade despite a rapid descent and the turn-in and road holding inspired confidence in an imposing environment.

An eight-speed sport automatic transmission is charged with the task of managing all of the gutsy triple-turbo torque and it does this admirably.

In sport mode gear-changes are aggressive and the transmission responds quickly to instructions from the steering-wheel paddles.

In normal mode the super-tight ratios shift almost imperceptibly and allow the engine to remain right on top of the torque sweet-spot.

On the flat the M50d’s acceleration is impressive with a figure of 5.4 seconds to get to 100kmh – even faster than the V8 twin turbo xDrive 50i petrol version.

But the swathes of torque really become evident when the X5 is shown a hill.

Straight line acceleration seems almost completely unaffected by even very steep gradients and the temptation to keep clicking up through the gears with the throttle buried is irresistible.

Even with snow tyres the grip and feel on dry asphalt was on a par with some high-performance sedans.

At higher speeds wind noise became a little intrusive and served as a reminder that aerodynamics are not an SUV’s strength.

The more-ish performance is accompanied by a satisfying soundtrack, which pertains to the complicated turbo performance going on under the bonnet.

Some of the sound is ‘piped-in’ through the entertainment system but it does compliment the driving experience rather than sounding fake or pretentious.

We particularly liked the guttural note when the third turbo cuts in.

Our driving was on the enthusiastic side of responsible, but with a careful toe, BMW claims the brute of the X5 range will return a respectable combined consumption of just 7.5 litres per 100km.

The X5 was perfect for negotiating the spectacular Cardrona Valley passes and made light of the imposing elements.

Our short journey from the top of a mountain to Queenstown was over all too quickly.

The $147,500 price tag might not fit everyone’s budget but you certainly get a lot for your money.

The low ride height that is partially to thank for the X5’s agreeable road manner, would no doubt hamper its off-road ability had we thrown it at more uneven surfaces.

When the new X5 is introduced later this year we hope it continues the same standard set by the current model and has a similarly epic diesel engine option.

You’re probably most likely to see an X5 doing the school-run in an affluent suburb, but try not to be too surprised if you happen to catch one at the top of a snow-capped mountain.

The overall combination of grip, torque and driving involvement makes the BMW X5 M50d a very capable package indeed.