THOUGH mechanically unchanged from the model introduced more than three years ago, a mid-life facelift has given the Mercedes-Benz M-class SUV not only a fresh, more aggressive face, but some welcome interior refinement in the form of new infotainment systems that enhance the audio and navigation functions. Still in place are the highway-eating road manners, top-shelf safety package and interior comfort of the superseded model, along with the same five-engine range as before, including the awesome 165kW/510Nm 3.2-litre turbo-diesel V6 fitted to the popular ML320 CDI and, in detuned 140kW/440Nm guise, ML280 CDI models.