Mercedes G 400d 2021 Review: Diesel Power, Efficiency, Insights

The Mercedes-Benz G 400d 2021 model stands as a testament to the enduring appeal of the G-Class lineage, merging military-grade durability with modern luxury and diesel efficiency. This diesel variant introduces a sophisticated inline-six engine that delivers impressive performance while promising lower running costs compared to its petrol counterparts. With its boxy silhouette and commanding presence, the G 400d continues to captivate enthusiasts who demand both on-road poise and off-road dominance.

Engine and Performance Excellence

At the heart of the 2021 G 400d lies Mercedes’ advanced 3.0-liter inline-six turbodiesel engine, producing 243 kW (330 hp) and a substantial 700 Nm of torque available from just 1,200 rpm. This powertrain propels the hefty SUV from 0-100 km/h in 6.4 seconds, with a top speed electronically limited to 210 km/h. Fuel efficiency is a highlight, achieving around 9.5 L/100 km in combined cycle testing, significantly better than the thirstier G 63’s 13.1 L/100 km. The nine-speed automatic transmission shifts smoothly, enhancing the engine’s refined delivery without the typical diesel clatter, making it ideal for long hauls.

Adaptive dampers play a crucial role in taming the G 400d’s 2.5-tonne mass, providing composed handling at urban speeds and stability on highways. Reviewers note minimal body roll and precise steering, despite the vehicle’s 13.6-meter turning circle, allowing confident navigation through tight spaces. On winding roads, the setup maintains strong roadholding, with the diesel’s low-end torque ensuring effortless acceleration.

Design and Road Presence

The G 400d retains the G-Class’s iconic angular design, featuring flared wheel arches, a upright windshield, and a prominent square bonnet that offers excellent forward visibility. Measuring 4.86 meters long, it towers over rivals like the Range Rover, exuding unmatched road presence that appeals to those seeking a statement vehicle. Standard 19-inch wheels (upgradable to 20-inch) and Pirelli Scorpion tires balance on-road grip with off-road potential, though some critique the ground clearance at 283 mm as modest for extreme terrain.

• Boxy aesthetics: Timeless design true to G-Class heritage.
• LED lighting: Adaptive headlights enhance night driving.
• Robust build: Ladder-frame chassis ensures durability.

Luxury Interior and Technology

Step inside the G 400d, and you’re greeted by a sumptuous cabin boasting premium leather, wood accents, and ample storage solutions. Dual 12.3-inch displays run the MBUX infotainment system, controlled via a central wheel or voice commands, delivering intuitive navigation, Apple CarPlay, and a Burmester audio system in higher trims. Headroom is generous, though rear legroom is tighter due to the upright design. The upright seating position provides a commanding view, perfect for the driver’s confidence.

Practicality shines with a 667-liter boot expanding to over 1,900 liters with seats folded, plus features like wireless charging and ambient lighting.

Safety and Driver Assistance

Earning a five-star ANCAP rating from 2019 protocols, the G 400d packs advanced safety tech including autonomous emergency braking, lane-keeping assist, adaptive cruise control, blind-spot monitoring, traffic sign recognition, and a 360-degree camera. These systems contribute to its secure feel, whether in city traffic or remote trails. The rigid structure and multiple airbags further bolster occupant protection.

On-Road Dynamics: Comfort Meets Capability

Despite its off-road roots, the G 400d excels on pavement thanks to adaptive suspension that absorbs bumps effectively in Comfort mode. Wind noise is present at highway speeds but not intrusive, and the ride remains compliant even on B-roads. Direction changes reveal the vehicle’s weight, yet it feels planted and predictable, outperforming predecessors in refinement. The diesel’s smoothness eliminates lag, making it a relaxed cruiser.

Off-Road Prowess: True to G-Class Legacy

The G 400d’s credentials shine off the beaten path, with low-range transfer case, three differential locks, and ample wheel articulation conquering obstacles effortlessly—even on road-biased tires. Ground clearance, approach (25 degrees), and departure (31 degrees) angles, combined with 700 Nm torque, make it a formidable 4×4. Testers praise its ability to handle dust trails and steep inclines without drama, proving the diesel suits rugged adventures as well as the V8.

• Low-range gearing: Essential for crawling.
• Differential locks: Front, center, rear for maximum traction.
• Articulation: Independent wheel travel tackles uneven terrain.

Running Costs and Practicality

While pricing positions it as a premium offering, the G 400d undercuts the G 63, with lower fuel and potential maintenance savings from the efficient diesel. Real-world economy hovers at 9-11 L/100 km, and its five-star safety adds peace of mind. Service intervals and warranty details align with Mercedes standards, though 19-inch wheels may increase tire expenses.

Pros and Cons

Who Should Buy the G 400d?

Ideal for buyers wanting G-Class prestige without V8 excess, the 2021 G 400d suits families, adventurers, and luxury seekers. It bridges efficiency and excitement, standing unique in the large SUV segment.

Frequently Asked Questions (FAQs)

What is the fuel economy of the Mercedes G 400d 2021?

Combined cycle figures are approximately 9.5 L/100 km, with real-world tests showing 9-11 L/100 km.

Does the G 400d have good off-road capabilities?

Yes, with low-range transfer case, differential locks, and 283 mm clearance, it excels off-road.

What safety features does it include?

It holds a five-star ANCAP rating, featuring AEB, adaptive cruise, blind-spot monitoring, and more.

How does it compare to the G 63?

The G 400d offers better efficiency (9.5 vs 13.1 L/100 km) and lower costs, with 0-100 km/h in 6.4 sec vs 4.5 sec.

Is the interior spacious?

Front space is generous, rear offers good headroom but tighter legroom; cargo holds 667 liters.

Final Thoughts on the 2021 Mercedes G 400d

The G 400d revitalizes the G-Class formula with diesel refinement, preserving its off-road soul and luxury appeal. It’s a compelling choice in a world eyeing electrification, offering timeless character and modern competence.