What is it?
Mercedes’ new M-class off-roader, now equipped with a grunty V8 diesel. The new V8, launched in the E 420 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 ML 500’s long- running three-valve-per-cylinder 5.0-litre V8 petrol engine and 82bhp more than the ML 320 CDI’s 3.0-litre V6 oil-burner.
The ML 420 CDI’s trump card, however, is its vast torque. With 516lb ft available between 2000 and 2600rpm, it is incessantly rapid.
What’s it like?
Quick. It’s the fastest accelerating M-class model save for the 6.2-litre V8 petrol ML 63 AMG. Despite tipping the scales at 2315kg, the ML 420 shoots from zero to 62mph in 6.5sec. And while it can’t quite match the ML 500’s electronically limited 149mph top speed, the ML 420 CDI’s in-gear performance is superior.