Mercedes Benz ML420 - way more economical

Mercedes’ new M-class off-roader, now equipped with a grunty V8 diesel. The new V8, launched in the E420 CDI late last year, is actually a 4.0-litre unit, not the 4.2-litre engine the badge on the tailgate suggests.

Based around the same four-valve-per-cylinder architecture as Merc’s smaller V6 diesel, it runs a pair of turbochargers and the latest common-rail piezo injector technology for combustion efficiency.

It produces 306bhp at 3600rpm – or exactly the same output as the ML500’s long- running three-valve-per-cylinder 5.0-litre V8 petrol engine and 82bhp more than the ML320 CDI’s 3.0-litre V6 oil-burner.

The ML420 CDI is beefier, way more economical, will realise a better resale value and removes that final weapon from the armoury of the committed petrolhead its even better to drive. The clincher is that Mercedes has priced the two cars at an identical £50,435. Big diesel engines make a great companion to luxury 4x4s and the Mercedes ML420 CDI benefits no end from just such a partnership.

With the ML420 CDI, you should get to within a couple of mpg of its quoted 25mpg figure without having to freewheel down hills. While this still wont make it the apple of the green brigades collective eye, its better than youd expect from something like a Ford Focus ST. Emissions arent eyewatering, with the big Merc returning 299g/km of carbon dioxide (ML500 319g/km).

The Mercedes ML420 CDI is an extremely capable car. Its unlikely to be taken off road but even when judged against road-biased rivals, it still makes a convincing case for itself. While it may not be the pick of the M-Class Range, it gives its direct opposition a real headache. Choices are only problematic when theyre not clear cut.

Mercedes Benz ML420