Meanwhile, wagons like the BMW X-Series and Volvo’s XC90, which lack low-range gearing, have been eating into Mercedes’ share of the market pie, suggesting that buyers don’t care whether their luxury 4WDs have off-road accoutrements or not.

So what to do? The solution is simple – go back to the basics and delete all the expensive off-road stuff on the mainstream models, but make it available as an optional extra. And go one step further, offer an "optical illusion" pack for those who like to give the impression they go off-road, but really don’t. This comprises a different-looking grille and some "under-ride" guards.

The proper Off-Road Pro pack, however, is the real thing, offering not only low-range and diff locks but ground clearance of up to 291mm – more than any non-military production 4WD anywhere.

Entry-level models for the luxurious second-generation M-Class in New Zealand are the ML 320 CDI and ML 350, powered respectively by the new generation 165kW/510Nm three-litre diesel and 200kW/350Nm 3.5-litre petrol V6. They start at $99,900 but a luxury pack, which many customers will order, brings the price to $116,900.

Topping the range for now is the $144,900 ML500 with a 225kW/460Nm five-litre V8 and a long list of extra features including the Airmatic adjustable air suspension.

The ML 63 AMG, displayed at the recent Frankfurt motor show, will be on sale here around August 2006.

It’s powered by a new 6.3-litre V8 that produces 375kW at 6800rpm and 630Nm of torque at 5200rpm. The outgoing ML 55 AMG pales in comparison with "only" 255kW and 509Nm.

All models use the 7G-Tronic seven-speed automatic transmission with the unusual Direct Select steering wheel gearshift and Speedtronic cruise control with speed limiter. The gears can also be selected manually using switches on the back of the steering wheel.

Design of the new model closely follows the original, its lines sharpened, crisper and more wind-cheating, with a Cd value polished to 0.34 from the previous 0.40, an improvement said to cut fuel consumption by up to 10 per cent. The wagon is 150mm longer at 4780mm, 71mm wider at 1911mm and 5mm lower at 1815mm with roof rails. Wheelbase has grown by 95mm to 2915mm.

The cushions and backrests of the rear seats are split 60:40 and can be folded down. Removable cushions can be ordered as an option, creating a level loading surface of 2.10m. The maximum load capacity is 2050 litres.

Despite the more generous dimensions, the M-Class is offered only as a five-seater. Those wanting a seven-seat Merc off-roader will have to wait for the new G-Class, coming next year.

The permanent 4WD and 4ETS traction-control systems incorporate additional functions such as Downhill Speed Regulation, Start-Off Assist and an off-road ABS system.

The Off-road Pro package includes the two-speed transfer case, manually or automatically selectable differential locks at the centre and rear and a modified version of the Airmatic air suspension system tailored to off-road driving, which can raise the ground clearance by 110mm to that 291mm and the vehicle’s wading depth to a maximum of 600mm.

Because the air suspension significantly improves ride comfort, Mercedes offers a road-going version as an option for the V6s and as standard on the ML 500. Airmatic teams up as standard with the Adaptive Damping System (ADS), which adjusts shock absorber response to suit the driving situation.

Mercedes engineers also redeveloped the front and rear suspension. The V6s use 235/65 R17 tyres while the V8 has 255/55 R18s.

The company says it "sets the pace for other off-roaders" safety. Its occupant protection system includes adaptive, two-stage airbags for the driver and front passenger, front sidebags and windowbags, as well as belt tensioners and belt force limiters for all seats. In a rear-end collision, the newly developed Neck-Pro crash-responsive head restraints provide additional protection for the driver and front passenger.

A newcomer is the anticipatory occupant protection system Re-Safe, an award-winning technology that provides a "reflex" response to critical driving situations where an accident may be imminent. Re-Safe acts in advance to pull the driver and front passenger seat belts taut, bring the fore/aft setting and the cushion and backrest angle of the electrically adjustable front passenger seat into a more favourable position and close the sunroof if there is a risk of the vehicle rolling over. The system is linked to the ABS, Brake Assist and the Electronic Stability Program whose sensors identify "dangerous" driving manoeuvres. .: