First, a bit of context. The official BMW terminology for these cars is "Sport Activity Vehicle" and, in the case of the X4 and X6, "Sport Activity Coupe".
These vehicles do not have a mud-plugging purity of purpose and it shows even before a wheel is turned in anger.
Whereas on the centre console of a Land Rover you will find a multitude of buttons patterned with symbols of varied geography, BMW's X models make do with one: Hill Descent Control (HDC).
The United Nations, a prolific user of Toyota Land Cruisers, is not BMW's target demographic. If you are the Singapore Armed Forces' procurement officer, I'd suggest you look elsewhere.
BMW would instead prefer you to think of xDrive as a handling- enhancing technology that can take care of the car in slippery conditions. The commercial name for BMW's four-wheel-drive technology, it works by varying torque between front and rear axles according to the degree of available grip, up to 100 per cent at either end. Under optimal conditions, it splits torque 40:60 front to rear.
This is useful not just off-road, but it also mitigates understeer and oversteer in enthusiastic driving. Under challenging conditions, it is assisted by Dynamic Stability Control, which brakes individual wheels and cuts engine power when grip is lost or the car threatens to surrender controllability.
A group of us power up into the Chiang Rai mountains, heading towards the peaks concealed enchantingly in low clouds. Here, the paths slithering up the densely vegetated slopes are narrow, damp and not always asphalt.
Our convoy, prodigious girth aside, handles them confidently. The diesel engines' generous muscularity is beyond question; that they spin eagerly through a broad and usable range in a passable impression of a petrol motor is a delightful bonus.
More importantly in these conditions, the xDrive system successfully and unobtrusively shuffles power fore and aft. The cars exhibit a reassuring surefootedness throughout.
The system's effect is best demonstrated by its absence when the only rear drive vehicle, the X5 sDrive 25d piloted by an enthusiastic Malaysian colleague, wags its tail threateningly on a hairpin before the stability control rights proceedings.
We thunder up the hills at a surprisingly rapid clip. BMW has prepared an off-road course on a hillside tea plantation. It includes mud and rocks on inclines, according to the gyroscope readout on our iDrive screens, of up to 35 per cent.
Some traditional facets of off-roading go untested, such as wading depth, approach angles and ability on wet grass, where grip is likely to be consistently scarce at all four corners at once.
These omissions are probably not inappropriate for a red coupe shod with 19-inch low-profile Pirelli P Zero tyres better suited for a racetrack. Nevertheless, the course is by no means a stroll in the park - one driver gives up halfway while trying to scale it on foot.
My driving partner and I contemplate the best driving style to overcome the rain-slicked paths. We are briefed by the accompanying BMW instructors to keep the engine between 1,500 and 2,000 revolutions for maximum chance of progress and to prevent wheelspin.
It turns out that such mental preparation is superfluous and the cars conquer the course easily.
Just point the car where grip looks most generous, let common sense deal with throttle application and off you go.
Steeper downhill segments are handled without drama by the HDC mentioned earlier, with speed determined by your courage and the cruise control toggle on the steering wheel.
This is not to suggest that you should attempt a military invasion in an xDrive. Nevertheless, this side of dedicated green-laning, there are few conceivable circumstances more challenging in everyday driving.
Certainly, the BMWs should prove no less adept than a Land Rover Defender at navigating your country mansion's unpaved driveway.
Back out on the open road, not much comfort seems to have been sacrificed at the altar of dynamism. The occasional intrusion does occur over sharper edged bumps, but all four cars mostly hum serenely along at a 120kmh cruise.
The cars have proven themselves very adept in a wide range of conditions and without doubt they are entertaining on the road. They also feel expensive, have sufficient gravitas and provide a "Command Position", in BMW's sometimes embarrassingly effusive marketing guff, to satisfy a market that has been moving away from traditional sedans for more than a decade.
In this, BMW can consider itself successful in its primary mission.
• The writer is a contributor to Torque, a motoring monthly published by SPH Magazines.