Mercedes ML320 CDI

To say it betters its predecessor doesn't do the ML320 CDI justice. Its leap ahead in ride comfort, build quality, visual appeal and driver dynamics means it is good enough to take on the Discovery, X5 and XC90 for class honours. We will bring you the definitive verdict in our group test closer to the car's UK launch.

What does the M in the new ML320 stand for? We reckon it is for Magic, because the fresh Mercedes off-roader is a massively appealing car that will take the fight to Land Rover, BMW and Volvo when it arrives here in September.

The ML's imposing grille, liberal sprinkling of chrome and substantial cladding may not appeal to everyone's taste, but there is no denying its powerful presence. Lower and wider, it drips confidence from every shutline. And it has a very American look - no surprise given it will be built in Alabama and the USA will be its biggest market.

We have already driven the ML350 petrol (issue 837) - now it is time to try out the ML320 CDI diesel. And what a superb engine it has: it is smooth, quiet and punchy, while still returning 29.4mpg on the combined cycle.

The engine is complemented by a 7G-Tronic automatic gearbox, which always seems to be in the right ratio at the right time. Body control is good, too; engineers have done a fine job of disguising the ML's size. Even on demanding roads, it seems taut and secure, and for such a large car handles with the composure of a family estate.

Only when you really start pushing hard does it seem like a heavy and bulky 4x4. The steering is light enough at low speeds to make urban work a doddle, while feeling direct when travelling faster, yet on optional Airmatic suspension, the ML is smooth and hushed.

Even small ripples and ruts - the downfall of many air-sprung cars - are smoothed. And at last Mercedes' build quality is back. The button-laden cabin is bank-vault solid, the ambience spoiled only by some hard shiny plastic on the console and a little too much chrome.

There is plenty of space inside, too - hauling six-footers around is a cinch, and the flat-floored boot is cavernous. The ML's all-wheel-drive system, adjustable ride height and downhill speed regulation will be plenty for most drivers' demands. However, the optional Off-Road Pro system (which is expected to cost around £1,200) adds underbody protection trays, a two-speed transfer case, diff locks and additional ground clearance, making the 4x4 a formidable mud-plugger.

Mercedes reckons the 320 CDI - and the 280 CDI which arrives early next year - will account for nearly two-thirds of total ML sales in the UK. No prizes to guess why. The 320 is the pick of the range - and impressive enough to the make the ML350 petrol look slow, thirsty and expensive by comparison.