The changes Mercedes have made to the 2008 M Class are mainly centred on extra equipment. It has worked hard to differentiate the two trim models in the range – SE and Sport – and has loaded them both with kit, to justify the price rises.

The SE is up to £250 more than the previous model, but comes with £2,100 worth of extra kit, while the Sport is £2,750 extra but features £3,470 worth of extras.

And this, says Mercedes, makes the M Class even more of an attractive proposition.

It has also worked on its engine line-up, which sees the petrol engine from the ML350 dropped, and the rest of the range tweaked for slightly better economy and improved emissions.

But even so, all models fall into the top tax band and the ML280 CDI and 320 CDI offer the best fuel economy, at an average of 34.9mpg.

Out on the road, both models offer plenty of performance, although the ML320 CDI is noticeably pokier when the two are driven back to back. There's a surprising amount of diesel engine clatter under acceleration, but at speed it's well refined.

Those seeking extra refinement should seek out the ML420 CDI, which offers petrol engine refinement, and plenty of go. This model will reach 62mph from rest in 6.5 seconds, before reaching 146 – 3.3 and 2.1 seconds faster than the ML280 CDI and ML320 CDI respectively.

Naturally running costs suffer, with an average of 31mpg and emissions of 292g/km.

Confusingly for buyers, consumption and emission figures are slightly lower for the SE than the Sport figures quoted here.

Wild ML 63 AMG

Performance fans are catered for by a pair of petrol engines, in the ML500 and ML 63 AMG hot rod. Running costs are predictably severe, but the red hot AMG model will find favour with those looking for extra bling and a wonderful V8 roar.

The Mercedes M Class is a competent performer on the road, with a surprisingly taut chassis for such a big car. It corners flatly, but suffers with steering vaguer than its key rival, the BMW X5.

View our Mercedes ML slide show

This can be addressed by specifying AirMATIC sports suspension, which adjusts the suspension, steering and gearshift patterns depending on whether Sport, normal or Comfort settings are selected.

With standard suspension, the ride can get upset by broken roads, while AirMATIC in its normal setting is a little more comfortable, but allows a little too much lateral movement. Comfort is too floaty for some, although very smooth, while Sport firms everything up for a more focussed drive.

The steering sharpens in Sport, but still lacks the feel afforded by the likes of the BMW X5 and Porsche Cayenne.

Handles well on- and off-road

The Mercedes M Class is also an impressive performer off road. We put the ML320 CDI through its paces on a very wet, slippery mud track, and despite its 20-inch wheels and road tyres, it was able to haul itself up some fairly challenging terrain. Our off-road test car wasn't fitted with the optional off road pack, which includes low-range gear ratios and height-adjustable suspension, but coped admirably.

All models are fitted with Mercedes' 7G-TRONIC seven-speed automatic transmission, driving all four wheels

Externally, the facelift Mercedes ML is distinguished by new bumpers, lights, and grille and alloy wheels.

The SE has 18- or 19-inch alloys depending on the engine chosen, black roof rails, tinted tail lights, larger automatic dimming and folding mirrors, black grille with chrome trim, twin exhaust pipes and a front cosmetic underguard, a powered tailgate, rain-sensing wipers and front and rear Parktronic parking sensors.

Inside it features a new multi-function steering wheel with new paddle shifters, new heated front seats with four-way electric lumbar support, dimming rear-view mirror and Mercedes' Audio 20 audio system with telematics, keypad, Bluetooth and aux-in connectivity.

It’s a surprise genuine leather isn't available for a £40,000-plus car, instead sporting Artico man-made leather upholstery covering the seats and door linings.

View our Mercedes ML slide show

The Sport model features extra bodystyling and larger 20-inch alloys to immediately set it apart from the SE model. It also includes bespoke instrumentation, rubber-studded stainless steel pedals, an Interior Lighting Package, and heated front sports seats, with four-way electric lumbar support seats upholstered in Alcantara and Artico.

Sadly there's no seven seat option, which will limit its appeal against the likes of the BMW X5 and Land Rover Discovery.

Full crash test scores

Standard safety kit includes Mercedes' PRE-SAFE anticipatory impact system, which adjusts the headrests and seat position to best prevent injury; and Mercedes claim its levels of passive and active safety are unmatched by any of its rivals. Other equipment includes anti-lock brakes, brake assist, four-wheel electronic traction control, electronic stability programme (ESP), trailer stability assist and acceleration skid control – resulting in a full five-star EuroNCAP impact test result.

We put some of its safety systems to the test, with tests involving braking from 100mph without steering to show its levels of stability, as well as avoidance tests at speed and under moderate and heavy braking. At all times, the M Class felt composed and under complete control.

It appears Mercedes has done enough to keep the M Class among the best sellers in its class. But the cost is heavy – it is certainly an expensive piece of kit.

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