Mercedes GLE 450 d 4Matic: the world’s most powerful passenger car diesel

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With the facelift of the Mercedes GLE, Mercedes has launched the most powerful diesel engine in production. The new Mercedes GLE 450 d 4Matic develops 367 ps (362 hp) and 750 Nm (553 lb-ft).

Following the exit from production in 2020 of the BMW X5 M50d’s 3-liter inline 6-cylinder quad-turbodiesel engine developing 400 ps (394 hp) and 760 Nm (561 lb-ft), Mercedes now offers the world’s most powerful passenger car diesel.

In the Mercedes GLE 450 d 4Matic, Mercedes has modified the OM656 3-liter inline 6-cylinder engine and maximum output increased from 330 ps (325 hp)/3,600 rpm to 367 hp/4,000 rpm, while torque increased from 700 Nm (516 lb-ft)/1,200 rpm to 750 Nm (553 lb-ft)/1,350 rpm.

In addition, the diesel engine is now supported at start-up and acceleration by an integrated starter generator that develops an additional 20 ps (19.7 hp) and 200 Nm (147.5 lb-ft) and is part of a 48V mild hybrid system. To achieve the 37 ps (36.5 hp) increase in power, Mercedes has increased the engine displacement from 2925 cc to 2989 cc by increasing the piston stroke from 92.3 to 94.3 mm.

Compared to the former Mercedes GLE 400 d 4Matic, acceleration from 0 to 100 km/h is achieved in 5.6 seconds compared to 5.7 before, and the top speed is limited to 250 km/h compared to 245 km/h before. WLTP consumption, on the other hand, has increased moderately from 7.2 l/100 km to 7.5 l/100 km.

The OM656 inline 6-cylinder diesel engine debuted in 2017 in the S-Class and is notable for its steel piston construction and aluminum engine block. The steel piston has the advantage that steel expands less than aluminum at high temperatures and is more robust than aluminum. Also, the improved Nanoslide coating of the cylinder walls has reduced friction and, thus, fuel savings.

The 6-cylinder inline instead of the V6 configuration allowed all catalytic systems to be installed directly on the engine. Moreover, supported by insulation measures and improved catalyst coatings, there is no need for engine temperature management during cold starting or at low load, which contributes to fuel economy on short journeys. So this engine is very well prepared for the future cold emission test on the first 10 km, included in the new Euro 7 standards.

Exhaust gas treatment is achieved with very little heat loss, by placing the catalytic converters very close to the engine. This engine also features multi-way exhaust gas recirculation (EGR) and combines cooled high-pressure and low-pressure EGR.

The OM656 uses a combustion process called stepped-bowl, named after the shape of the combustion bowl in the piston. The new stepped bowl has a favorable influence on the combustion process, which is much more efficient due to better combustion. With this engine, Mercedes has no problem meeting Euro 6d and Euro 7 standards. RDE road tests have shown NOx emissions well below the required limits of 80 mg/km NOx for Euro 6d and 60 mg/km NOx for Euro 7.

At the same time, the Mercedes GLE 300 d 4Matic features the most potent 4-cylinder passenger car diesel, available also in the new GLC. With a displacement of 2 liters, it develops 269 ps (265 hp) and 550 Nm (405.6 lb-ft) and benefits like the 6-cylinder engine from a 48V mild hybrid system with an integrated starter of 20 ps (19.7 ps) and 200 Nm (147.5 lb-ft).

The model range is completed with two PHEV models. The new Mercedes GLE 400 e 4Matic delivers 381 ps (376 hp), 38 ps (37.4 hp) more than the previous model, while the Mercedes GLE 350 de 4Matic remains almost unchanged, with a slight increase of 3 ps (3 hp) for the 2-liter turbo engine from 194 to 197 ps (191 to 194 hp).