It can dispose of the kilometres with ease, yet it also provides a relaxing yet high performing drive.
What makes the X5 so special is its combination of power and handling - it all seems unrealistic for a vehicle which weighs in at around 2.2 tonnes.
The engine is a 3-litre, six-cylinder unit, diesel-fed, and it is rated with mammoth power outputs of 280kW and 740Nm of torque (2000rpm to 3000rpm).
The latter promotes vigorous mid-range surge, thanks to the inclusion of triple turbochargers, so the immediate boost and response to throttle request is almost uncanny.
The power comes in unassumingly, but the X5 in this form has speed to envy. I didn't extend the test car much beyond the legal limit because of the ever-vigilant highway patrols which operate in that part of the country, but I can report that it lunges to high speed and it is enjoyable to feel that surge.
For the record, BMW claims a standstill to 100km/h time of 5.4sec and a top speed of 250km/h really got this one right which is some indication of its performance potential.
And, what's more, it is a bit of a fuel miser. During the drive to Christchurch it was constantly listing an average of around nine litres per 100km (31mpg) with an instantaneous figure of 7.5l/100km (37mpg) available at a steady 100km/h, the engine turning over at a very lazy 1500rpm. BMW claims a 7.5l/100km combined cycle figure for the M-series X5; I wouldn't argue against that given perfect conditions.
Power is transferred through an eight-speed automatic gearbox. Other than a little sound which has been manufactured into the engine exhaust, the driveline is quiet, smooth and sophisticated, shifts can barely be detected and the right ratio always seems to be selected so momentum is ushered in depending on the driver's wants and needs.
The M50d is little different from its stablemates to drive, other than the extensive delivery of power, of course, but it is agile, almost nimble, with directional steering, firm steering feel and accuracy into a corner that belies its bulk.
The test car had been used in Queenstown for BMW's Alpine xDrive experience at the Cardrona snow farm, and it was riding on 20in Pirelli Scorpion ice and snow tyres. Surprisingly, they were quiet on the trip and did not wilt under cornering pressure.
The M50d has control in a corner which promotes high cornering speed. It must be said, though, that the suspension is well-firmed. There's a bit of a jiggle through the suspension over ruts and bumps and that is transmitted in-cabin.
Thankfully, fabulous seats prevent occupant jarring, but the suspension is engineered for high performance handling, and it does that job well. Take into account, too, that BMW has incorporated complex electronic and mechanical components into the suspension and they are designed to retain balance.
During the 500km journey I ventured off the seal only once, for a picnic lunch near Lake Pukaki.
A short dirt track led down to the lake, with a steep hill incline on the way back to the road, it was slippery after overnight rain, but the X5's clever X-drive power proportioning system kept all wheels driving evenly through the slush.
X-drive is a complex system which works with extensive electronic override systems such as traction and stability control and a host of other safety features aligned to the ABS sensors.
BMW isn't short on promoting safety, and the X5 as a range incorporates the latest in that technology.
After leaving Fairlie I was pushing hard through the hills towards Geraldine, the roads were deserted, and I felt the electronic systems working for me as I chose, forcefully, the best line through a corner, giving an intervention from which the driver can gain a lot of confidence.
But that's what you would expect from BMW. It is a forward-thinking company and when you are spending $168,000 on a vehicle it's nice to know it is state-of-the-art in terms of technology.
That spending also buys a high level of comfort and convenience items. Of note are the sequential shifting gear change paddles, heads-up speed display reflected on to the windscreen, i-Drive navigation of audio, communication and sat nav, full leather with heated seats and comprehensive trip computer.
I've often written how engine torque is one of the most important ingredients in a vehicle's engine. The X5's twin-camshaft unit pumps out the highest amount of torque I've experienced, and yet it displaces only 2993cc.
It is quite magical how it delivers such quick acceleration and consequent speed. While even the best of New Zealand's roads are speed limited to 100km/h, I can see how useful that amount of power is, especially when overtaking, and how it would be on the unrestricted, multi-lane roads of Germany.
The X50d is a tribute to the prowess of BMW's performance arm.
The numbers
Price: BMW X5 M50d, $168,000.
Dimensions: Length, 4857mm; width, 2010mm; height, 1766mm.
Configuration: Six-cylinder longitudinal, four-wheel-drive, 2993cc, 280kw/4000rpm-4400rpm, 740Nm/2000rpm-3000rpm, eight-speed automatic.
Performance: 0-100km/h, 5.4sec; maximum speed, 250km/h.
