What's this then?

This is the new Mercedes G-Class, or G-Wagen, the firm's big, luxury off-roader.

It looks exactly like the old G-Class to me.

Indeed it does. You're going to have to squint, and possibly break out a tape measure, to tell the difference between this one and the old one, from the outside at least. The styling has barely changed at all (that's the way G-Class customers like 'em), but the G-Class is longer (by 53mm) and wider (by 21mm) than before. Even if it has the same old clamshell bonnet and exposed door hinges.

What's actually new then?

The body is new, even if it doesn't look it, and the frame (still a ladder chassis) is now 55 per cent stiffer than before. Ride height, thanks to re-worked wishbone-front and beam axle-rear suspension, has increased to 270mm and the G-Class can wade through 700mm of standing water without a snorkel.

So it's still a serious off-roader?

Oh, yes. Three locking diffs and low-ratio gears see to that, as well as a 30-degree approach angle, 26-degree breakover angle and a 31-degree departure angle. And bear in mind that this is the basic version - Mercedes has its eye on making more extreme, hard-core off-roading models.

There's adaptive suspension on offer, allowing you to choose between Comfort, Sport, Eco and Individual modes, and a special G-Mode too, that sets up the suspension, throttle and steering for serious off-road work.

How about engines?

For now just the G500 V8 turbo petrol is available, with 422hp and 610Nm of torque. Mercedes claims 25mpg on average, and emissions of 263g/km, so it's not going to be cheap to run. It drives all four wheels through a standard-fit nine-speed automatic gearbox. Hold on though, because more versions are coming - AMG V8 and V12 versions are planned, as is a new diesel G with the latest 2.9-litre straight-six from the S-Class.

What about the cabin?

That's where you'll notice the biggest changes. Instead of lots of indestructible plastic, as in the G-Wagen of old, you now get the all-glass cockpit from the E-Class and S-Class, with two massive 12.3-inch displays for the instruments and infotainment. And the G-Class is now stuffed with all the expected luxury technology appointments. You can spec it with luxurious heated and massaging multi-contour seats. There's also more space, with 150mm of extra rear legroom.

Ola Källenius, Member of the Board of Daimler AG responsible for Group Research and Mercedes-Benz Cars Development, said: "The new G-Class is setting the bar higher still in all relevant areas - in terms of performance both on and off the road, as well as with regard to comfort and telematics. Our 'longest-serving' model series is therefore ideally equipped to continue its success story. In short, the new 'G' is still a 'G', only better."

Neil Briscoe - 15 Jan 2018