Six-cylinder diesel coming to Mercedes G350d

MERCEDES-BENZ is set to expand the all-new G-Class range in Australia next year, with the arrival of a turbo-diesel version to sit alongside the sole AMG G63 variant that arrives this August.

To serve as the entry-level version of the W464-series G-Class in this market, the G350d is expected to launch sometime in the second quarter of 2019 with a pricetag of about $175,000, providing a useful saving on the $247,700 (plus on-road costs) that the company is commanding for its petrol-powered 4x4 flagship.

Additionally, the diesel-powered G-Class will usher in Mercedes’ all-new 3.0-litre in-line six-cylinder engine first seen in the latest S-Class limousine, offering a displacement of 2927cc and four valves per cylinder, for a power output of at least 230kW and more than 650Nm of torque.

This compares to 430kW and 850Nm delivered by the AMG G63’s 4.0-litre bi-turbo petrol V8 petrol. As with the latter, a nine-speed 9G-Tronic torque-converter automatic transmission will most likely send drive to all four wheels.

While a diesel-powered G-Class would provide extra volume for Mercedes-Benz Australia/Pacific, the outgoing G350d – which is priced from $164,611 and is powered by a 180kW/600Nm 3.0-litre V6 – only accounted for about 15 per cent of total range sales.

This figure is also roughly representative of what the old G350d managed worldwide, highlighting the rich model mix that the G-Class has come to attract.

Mercedes is keen to clean up the reputation of the diesel engine. As with all diesel engine providers in the aftermath of the Volkswagen Dieselgate emissions scandal that broke in late 2015, it is understood that Daimler AG has delayed the release of the new engine in the G350d as ultra-rigorous real-world testing, or RDE Real Driving Emissions procedures, are being finalised for the powertrain to meet its Euro 6 emissions rating.

To help achieve the above goals, this all-new diesel includes a stepped-bowl combustion process, introducing a shape that promotes a higher burning rate due to very specific airflow circulation properties, according to the company, as well as emissions-reducing components that are installed directly on the engine, for improved cold-start engine temperature management and lower heat loss in the exhaust after-treatment areas. Or, in other words, thermal control is greatly improved. Along with providing better fuel economy – the AMG G63’s Euro combined average is 13.1 litres per 100km while the outgoing (and at least 170kg heavier) G350d managed less than 10.0L/100km – the new in-line six diesel would bring greater off-road capability for Australian buyers of the G-Class, as it would most likely not come with the rear anti-roll bar and other high-performance enhancing on-road favouring elements that limit the petrol flagship’s ability to go off-road.

Whether a smaller-displacement in-line six-cylinder turbo-petrol-powered G-Class is in the pipeline is still unknown, although one Mercedes-Benz source said that low anticipated global volumes for such an engine would make that an unlikely prospect, particularly given that in other markets, the 310kW/610Nm 4.0-litre twin-turbo V8-powered G500 would achieve much the same result with very little real-world fuel-consumption penalty due the 2.5-tonne nature of the G-Class.