IT’S the leap of faith most Land Rover owners will, perhaps mercifully, never get to experience.
You’re driving down a country lane behind the wheel of a Range Rover Sport, when the route is barred by a mud-spattered off-road vehicle.
Out pops specialist 4x4 instructor Ronnie Dale to direct you over the edge of a precipice in the direction of what he gleefully calls Ronnie’s Stream.
You don’t appreciate the gravity of this greasy slope until it’s too late and the car is slithering towards a nosedive. Then you beg forgiveness, take your feet off the pedals and let the vehicle’s Hill Descent Control do the rest.
The Range Rover picks its way down with the dexterity of a mountain goat, until reaching terra firma – except that it’s not, you’ve plunged into a narrow, winding river, pock-marked with boulders and with twisted tree roots sticking out from the banks.
A quarter hour later the car emerges from the underworld for some brief on-road respite before the next stage kicks in.
In the space of 24 hours we negotiated eight hardcore off-road sections in four different Land Rover heavyweights – a case of off-road overload, and the best fun you can have on four wheels.
The company is riding the crest of a wave at present, the recently-launched Liverpool-built Evoque scooping awards by the bucketload while sales of some of the more established models have boomed, taking Land Rover close to manufacturing capacity.
Four of them – Discovery, Defender, Range Rover and Range Rover Sport – have been given upgrades for 2012.
And though the changes are far from dramatic, they strengthen the appeal that has secured Land Rover’s high-riding position both on and off-road.
Land Rover owners know their vehicles are loaded with the most advanced technology around; not all will appreciate just how far they can be pushed.
Never mind mounting the kerb at a supermarket or escaping the sludge in a racecourse car park, this is hardcore.
The first off-road section in the Discovery 4 included two miles on the old Roman road Dere Street, which ran from York into Scotland.
The drive opened up some of the most spectacular moorland views and autumn colours you could hope to experience anywhere, and included sluicing through a reed bog with ruts so sheer and uneven that the Disco was tossed around like a rag doll, but was never in any danger of getting stuck.
Then from the splendour of Floors Castle, seat of the Duke of Roxburghe, it was a two-hour Defender assault in pitch darkness - expedition grade off-roading, through dense Scottish forest in driving rain.
The high-power Xenon headlamps on full beam added a haunting, almost surreal, quality to the surroundings as the streams, tracks and woodland glades appeared like animations from a commando or Tomb Raider-style computer game.
Some of the slopes were near vertical while a section on narrow ramps across consecutive lakes felt like a night-time passage through The Everglades.
And at the completion of a trek along a boulder-laden stream we plunged into a lake, headlights below the surface and submarined through to a slope on the opposite bank.
This was off-roading at its most demanding in the most iconic model in the Land Rover line-up, which now has a smaller 2.2-litre diesel engine affording the Defender better fuel economy and reduced emissions.
Day two saw a switch to Range Rover and Range Rover Sport models in an equally demanding programme – zig-zag ruts bubbling with mud, a drive high onto Kippet Law grouse moor and a pair of river crossings topped off with that nerve-jangling plunge.
Both these models also feature upgrades for 2012, the Range Rover benefiting from a new 4.4-litre TDV8 diesel with eight-speed auto transmission and the Sport getting a powered tailgate and new side grilles among its enhancements.
With more punch, leaner performance and unrivalled levels of hardware, Land Rover has underlined its position in the 4x4 pecking order – king of the hill by a country mile.