New Mercedes G-Class prototype review: mild-hybrid power suits the G 450 d

Verdict

We’ll have to wait until we drive the final production version of the Mercedes G 450 d before giving a full verdict, but early impressions of this pre-production model, with its ISG-assisted six-cylinder diesel engine, impresses with improved performance, enhanced economy and lower emissions. A revised MBUX user interface and driver assistance package brings the Mercedes G-Class into line with the rest of the maker’s line-up, too.   

Mercedes will refresh the G-Class range in the coming months, and Auto Express has joined the team developing the car as it goes through its final-stage testing. The EQG electric version will undoubtedly steal the headlines when it arrives, but the company has also been working on more conventional petrol and diesel models, and as such, we bagged some time driving the new G 450 d. 

This car is powered by the same base engine as the outgoing G 400 d, but Mercedes has added an ISG (Integrated Starter Generator) 48-volt mild-hybrid system to the 3.0-litre six-cylinder diesel engine – boosting not just performance, but also economy. 

Combined output is around 385bhp, with that ISG adding around 20bhp. It’s the torque where the system makes the biggest impact, however, adding around 200Nm to the six-cylinder diesel’s already significant 750Nm.

That’ll undoubtedly result in a performance uplift, which will see an improvement to the 0-62mph time. But with all that torque available from as little as 1,350rpm, it’s all-round driveability on and off-road where the benefits are best experienced.

Such are the tweaks to the internal friction of the engine, Mercedes has added hill descent control to the driving package, as the engine braking in low range is reduced over the outgoing model. This, added to the inclusion of the ISG, manifest in significantly improved fuel consumption, with the G 450 d showing an easy 30mpg+ on the trip computer during our drive – a tangible improvement over the 25.7mpg WLTP combined consumption figure for the outgoing car. 

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Indeed, Mercedes has learnt lessons in its development of the forthcoming electric G-Class, which help it eke out as much economy as possible from the iconic, but far from aerodynamic G-Class. Keen-eyed spotters will notice the A-pillars have an additional moulding on them, while the gutter above the windscreen on the roof now features an additional spoiler, aiding aerodynamics, but also benefitting interior refinement with a significant reduction in wind noise on the move. Further to this, the engineers have added some extra insulation material, too.  

That quietness, allied to finer control from the suspension due to some damper tuning on the new model, make for a more comfortable G-Class driving experience. The G 450 d will also adopt Mercedes’ latest driver assistance technology like lane-keeping assist. 

That’s all accessed via the new MBUX interface, which sees the G-Class lose the turn-and-push controller for a new touchpad on the centre console. Within that infotainment system there are more driver modes, with a new Trail selection for light off-road tracks joining others including Individual, Comfort, Eco, Sport, Sand and Rock. 

With the G 450 d retaining its three locking differentials and low-ratio transfer case, this revised G-Class is still able to clamber, crawl and climb like a mountain goat, making it a hugely competent, all-round package. With capabilities that few will ever really need, some of the compromises that once were part of that have been significantly reduced. The G-Class is more comfortable and economical, but just as mighty as it always was.