Lamborghinis are lousy for furniture removals. They may have a number of other qualities but if you need to move a double bed, a Gallardo just doesn't cut it. Want to know what the Mercedes ML320CDI is rubbish at? Nothing. This is one of the few cars that can turn its hand to any automotive task with a reasonable degree of competence. Find a twisty section of blacktop and it can entertain. It'll splash through axle deep mud and it'll even tool easily through city traffic with reasonable economy. It's practical, well built and good looking. You may have to pay for the privilege of getting hold of this automotive decathlete but one suspects you won't be disappointed.

Let's start with that astonishing powerplant. Unlike old Mercedes diesels, which were rather lumpy five-cylinder units, this latest is a creamy V6 with four valves per cylinder. Rated at a healthy 224bhp, it's got more than enough muscle to haul the 2110kg Mercedes around. In fact, its torque figure of 510Nm is even beefier than the V8 ML500 version. What's more, you'll reach this figure at little more than tickover and sustain it across a broad plateau from 1,600 and 2,800rpm. The switched on will realise that this makes the ML320CDI an extremely adept tow vehicle. This common rail direct injection engine has quickly proved a winner for the Daimler Chrysler group and it's being plumbed into all manner of Mercedes and Chrysler models to great effect but the M-Class vies with the C-Class for the most attractive vehicle to use the 3.0-litre unit.

Slotted beneath the low-slung bonnet of the M-Class, this engine will punch the car to 60mph in a smidgeon over nine seconds and on to a top speed of 130mph. Combined fuel economy is rated at 30.1mpg which is little short of astounding given the size, weight and performance of the car. With a 95-litre tank, the ML320CDI therefore excels as a long distance cruiser, capable of notching off over 800 miles between refuelling stops.

"The M-Class hasn't always been overwhelmingly convincing. Drive an ML320CDI and prepare to backtrack"

Mercedes could have put this engine into the old M-Class but to do so would have been to create a glaring mismatch. The latest model takes all of the old car's shortcomings and comprehensively rectifies them. To be fair to the M-Class, although the quality control of the initial batch of cars produced from the Tuscaloosa plant in Alabama were rather patchy, latter models from the Austrian facility at Graz were a whole lot better screwed together. Some of the interior materials were a little half hearted but a nicely specified M-Class was, until the introduction of the Land Rover Discovery 3, still probably the best looking of all the big 4x4s.

The lines have worn so well that the current generation M opted for an evolutionary look, keeping the same sporty stance and raked forward C-pillar but adding more pronounced wheelarches and a rising swage line along its flanks that may look a little too Toyota RAV4 for more conservative tastes. It marks a definite swing towards the sports end of the sports utility market and differentiates the Mercedes nicely from cars like the Land Rover Discovery and the Volkswagen Touareg. The next X5 will have its work cut out to offer styling quite as slick as the M-Class.

Although the sharply raked back windscreen and contoured body panelling give the M-Class a sporty, compact appearance, the tape measure shows just how artful its stylists have been. It's 150mm longer than its predecessor, 71mm wider and the wheelbase has grown by 95mm. It is also 7mm lower. Aerodynamics have been improved from a cd value of 0.39 to 0.34 with fuel economy savings of as much as ten per cent.

Fitted as standard is Mercedes' renowned 7G-TRONIC seven-speed automatic transmission, widely renowned as the best automatic gearbox in series production. Intelligent shift management allows the gearbox to plug into the engine's power band while being more efficient in terms of fuel efficiency than any other automatic. The Direct Select function allows drivers to select gears 'manually' using a selector level positioned close to the steering wheel. Steering wheel-mounted gearshift buttons are also offered.

Both the front and rear suspension has been thoroughly revised for this generation M-Class, with a double wishbone front and a multi-link rear arrangement. For those that really want the ultimate in ride quality, Mercedes also offers an Airmatic air suspension system option that teams up with an Adaptive Damping System that adjusts the responses of the shock absorbers according to the situation in hand. There's also an optional off-road biased air suspension option which adds a two-speed transfer case with an off-road ratio, manually or automatically selectable diff locks and a version of Airmatic which raises ground clearance by 110mm to as much as 291mm. This means that the M-Class will now ford water up to two feet deep.

For all the slick styling and impressive engine, the single biggest change that will transform this M-Class' chances is the improved quality of the interior. Gone are the brittle plastics and uninspired ergonomics of the old M-Class, replaced by something that's far more in keeping with Mercedes premium image and pricing. The dashboard features a pair of cowled main dials with a digital information panel between, while the centre console retains the styling of the latest E-Class models. Although it's not what you'd call packed with surprise and delight features, the cabin now befits a vehicle of this class.

If you can overcome the upfront price, the ML320CDI is surprisingly affordable to run. Insurance is manageable, fuel economy is good and the residual values look set to be so strong that the all-important pence per mile figure looks very favourable. Whoever said the best things in life are free had obviously never driven a Mercedes ML320CDI.