Fired up with a push-button starter, which requires the key fob to be in the vicinity, the four-cylinder twin-stage turbo common-rail diesel delivers its maximum power at 3,750rpm. Top torque of 450Nm kicks in across a 1,500-2,500rpm plateau.
AdBlue is required to achieve the mandatory Euro6 emission standard and is held in a 17-litre reservoir.
Flick the auto gearbox’s shift lever to the left and you go to manual, but there is rarely going to be any need to do that on-highway. The facility could prove useful in the rough, however.
The X-Class’s 4Matic four-wheel drive is selectable on 2.3-litre models, but permanent on the soon-to-arrive 3.0-litre. To select it, you turn a knob on the dashboard. Turn it again and you engage a low-range set of gears to go with it. The mode you are in is shown on the instrument panel.
If the going gets wild then the front passenger has a grab-handle on the nearside A-pillar to cling on to, while the two outermost rear passengers can hang on to handles on the B-pillars.
Pull away from rest in an X-Class and the first thing you notice is how quiet the engine is. All it seems to emit is a muted background burble, and the gear-change offered by the auto ’box is so smooth you barely realise you are moving from one set of cogs to the next as you gather speed.
Bearing in mind that the truck weighs 3.3t fully laden, the level of on-the-road performance it offers is impressive. The strength of the auto gearbox’s kick-down is such that you can overtake with confidence whenever it is safe to do so.
The handling of double-cab 4x4 pick-ups has improved steadily over the years, and with the X-Class it has well-nigh reached its apogee. Push it hard through a bend and you soon realise you could have probably pushed it even harder without coming unstuck. The steering tightens nicely, the suspension responds exactly as you hoped it would, assuming the highway’s surface is reasonably smooth, and all is well with the world.
Drawbacks? The suspension needs to be retuned to match Britain’s appalling road surfaces with an eye to improving the ride, and there was slightly more wind and road noise from the rear of the vehicle than is acceptable. The rear screen is on the shallow side, too, which means vision rearwards isn’t quite as good as it should be. The frame required by the aforementioned sliding window doesn’t help.
The X-Class is a perfectly competent performer off-road, happily squelching across fields and fording shallow streams. It is neither designed nor intended for really demanding off-roading – it’s not in Mercedes-Benz Unimog off-road territory – but if all you need to do is get up a steep, narrow, muddy rural track then you shouldn’t be disappointed.
Having said that, the X-Class’s steep price tag might make you think twice before you take it anywhere where it might get muddy or (whisper it quietly) scratched. Downhill Speed Regulation is installed to prevent the truck descending steep, slippery inclines too rapidly.