But those hopes are set to be dented after the German company's development team failed to fit the flagship eight-cylinder diesel engine into right-hand drive versions of the rejuvenated range. Therefore, it will not be available when the range goes on sale next month.
Boasting one of the most powerful passenger car diesel engines in the world, the V8 ML400 CDI blends a top speed of 132mph with combined fuel economy of more than 26mpg. The problem is that ancillary equipment on the new V8 turbodiesel engine fouls the steering system on the right- hand drive platform.
The UK engine line-up has not changed because of the problems, with 3.2- and 5.0-litre petrol engines, along with a hot AMG version offering 5.4-litres and 347bhp. In all cases, CO2 emission levels are sky-high, starting at 324g/km for the 320 and 350g/km for the 500, guaranteeing 35% tax treatment under the new CO2-based company car tax from April.
The diesel scrapes in slightly lower, with 248g/km from the 2.7-litre engine, offering 34% for the first year only, before joining the rest of the range in the 35% band.
Though most onlookers at first glance would be hard pressed to distinguish between new and old versions, more than 1,100 modifications have been made to improve the car's off-road capabilities, without detracting from the way it behaves on normal roads. Enhancements have also upgraded comfort and increased convenience for the driver and passenger alike.
The bumpers have been reworked to include integrated fog lamps and they now offer greater impact resistance, while the car's headlamps get the trendy clear-glass treatment. All models now ride on restyled 17-inch alloy wheels.
More readily noticeable, the new-style centre console has a more upmarket appearance, thanks to the adoption of wood trim across the range. It looks more car-like, featuring neat dials with LED markers to make it easier to set the climate control system. More stowage space has also been added.
On the safety front, major new standard features include side impact window bags, double ISOFIX child seat mounting points in the rear and headlamp assist, which automatically activates the lamps when light fades.
It might look much the same as before, but the new M-class feels different from behind the wheel - especially if you opt for the range-topping ML500.
From your first dab of the accelerator it is clear the flagship model has been given more oomph in order to take on the forthcoming new Range Rover. Its silky-smooth petrol V8 is quicker off the mark and proves faster all-out than the ML430 it replaces.
Slightly firmer damping is aimed at promoting sportier handling without detracting from highway ride comfort, but I thought the result was a bouncy, uneasy ride over some of the more bumpy East German road surfaces included on the test route.
The upside of the compromise came into focus during a particularly demanding off-road course based on a former open cast mine. Here, the long-travel suspension soaked up the punishment with aplomb as the car hurtled along a rough track at speeds approaching 100mph.
The ride was also impressive over the rough and tumble terrain most owners would never dream of attempting. They are also unlikely to feel the benefit of the car's improved 4-ETS system, which brakes individual wheels to improve off-road traction.
In its latest form, ETS makes sure the car's speed down impossible-looking slopes never exceeds 5mph, much in the same way as Land Rover's Hill Descent Control. An added benefit is that it also holds the M-class steady before moving off on steep gradients.
A five-speed dual range automatic transmission is standard from the ML320 upwards and a new optimum gear speed control facility allows better engine braking on downward slopes, or maximum acceleration during overtaking manoeuvres.
Although panelwork is as before, lots of detail improvements have made the M-class appear less bland and this tough vehicle's interior now looks more like that of a luxury car.