The 2018 Mercedes G‑Class modernises a legend

And Mercedes’ answer is? Improve the G’s on-road manners, keep its off-road ability, tighten up the panel gaps and pile in the premiumness – but most of all keep it looking recognisably boxy and tough. Thus the machine having its world premiere at the Detroit Auto Show appears, on the outside at least, like it’s 1979, LED headlights notwithstanding.

The body is in fact, all-new, but the upright windscreen, raised bonnet, external hinges, chunky door handles, rain gutters, non-flush windows, side-opening tailgate and indicators atop the wheelarches all clearly belong to another automotive era. For many, features like this will be a welcome relief from SUV sameness; for Mercedes they are the “iconic design elements” of its longest-serving model that must be kept at all cost. Mercedes is even promising the doors will make the same distinctive sound (a clatter like a caravan door) when shut. 

Monocoque construction, air suspension, even something as common these days as hill descent control? No. The daddy of all Mercedes 4x4s heads into its fortieth year eschewing such refinements. It continues to be based on a separate ladder-frame chassis, with a rigid rear axle and all the heavy duty off-roading kit for which the G has always been known: permanent all-wheel drive with low-range gears and three – front, centre and rear – 100 per cent lockable diffs. Anachronisms? Not if you are stuck in the middle of nowhere they’re not, or towing 3.5 tonnes on unmade roads.

While the Geländewagen might have fathered a whole range of Mercedes SUVs, from A to S, the new one is clearly no SUV that goes weak at the sight of a muddy puddle. Mercedes says wheel articulation, ground clearance, wading ability and approach/departure angles are all improved on the outgoing model – which was as go-anywhere as the best of them. 

The diff locks may be push-button easy but there’s still no user-friendly Terrain Response set-up, just a new G-Mode. This imposes off-road-biased parameters on systems like dampers, steering, throttle response and transmission. But at first sight, it doesn’t appear as do-it-all as rival systems.

The biggest improvement promises to be on-road. New front suspension – struts and double wishbones for the first time – and electro-hydraulic rack and pinion steering (instead of recirculating ball) are said to make the new G “significantly” more agile, comfortable and feel-full to drive than the outgoing version. Merc’s Dynamic Select driving mode selector is available for the first time, as are driving assistance systems such as Park Assist. 

It’s lighter, stiffer and larger than it was before. The body is 53mm (2in) longer and 121mm (5in) wider and it shows inside with an impressive (and needed) extra 150mm (6in) in rear-seat legroom, as well as more cabin width and a slightly bigger boot. The body is mostly steel but the new G weighs in at 170kg less than before thanks to aluminium for the wings, bonnet and doors. It is also 55 per cent more torsionally rigid than before, says Mercedes.

All this can be enjoyed from a cabin that retains some familiar G design characteristics but whose makeover centres more on S-Class level luxury and technology, including (as an option) the firm’s configurable wide-screen dashboard display. There are more comfort options, too. In 1979 any G-Wagen, as it was then called, pummelled your backbone whenever you drove it; in the new one, you have just to push a button for a massage if you opt for the Active Multicontour Seat package.

There will, in due course, be a range of G-Class variants, with different wheelbases and body styles. For now, it’s a five-door estate or nothing, with – another G-Class signature – a side-opening tailgate and externally-mounted spare wheel. And no, they still aren’t making it open from the left side so it is safer to use in countries where we drive on the left.

In its time the G-Class has been all things to all people, from the Pope and wadi-bashing Middle Eastern potentates to farmers, explorers and the military. But its latterday success as the blinged-up ride of choice for movie celebrities and rap stars has become an enduring image, fixing the G-Class in a sort of parallel 4x4 world. That’s true even in the UK where six out of 10 old-model Gs, of the mere couple of hundred a year they sell, have been the £136,000 571bhp AMG 63 model. The rest have been the entry diesel at a mere £92k.

Power is central to the G’s celebrity appeal and while the engine range is yet to be confirmed the likely good news for celebs everywhere is that there will be a G with gee-gees galore. These, however, will be courtesy of the new twin-turbo 4.0-litre V8 rather than the old 5.5 lump. No matter; there’s still as much as 612bhp available… There will also be a diesel, most likely in the form of Merc’s new 2.9-litre straight six. The 350d version of this engine in the S-Class has 282bhp and 442 lb ft, and the 400d version 335bhp and 516 lb ft – it’s Merc’s most powerful diesel ever.

Price? Boxy and tough mud-plugger it may still be at heart, but its top-end position is well established now and the new one won’t change that. It will cost from around £95,000 when first UK deliveries are made in the summer.

Now only one thing is missing in the reborn 4x4 stakes: Land Rover’s response. Will its route to reinventing the greatest 4x4 icon of all follow the same path as the Germans? We’ll know that when the covers come off the reborn Defender later in this 70^th anniversary Land Rover year.