Mercedes-Benz has begun sales of two diesel models of the new GLE SUV which already comply with the coming Euro 6d emissions standard. Delivery of the first vehicles begins in spring of 2019.
The OM 656 six-cylinder diesel engine comes with 243 kW (330 hp) and 700 N·m of torque in the GLE 400 d 4MATIC (combined fuel consumption: 7.5-7.0 l/100 km; combined CO2 emissions: 199-184 g/km) and costs €76,100.50. The GLE 350 d 4MATIC with an output of 200 kW (272 hp) and 600 N·m of torque (combined fuel consumption: 7.5-6.9 l/100 km; combined CO2 emissions: 198-184 g/km) is available from €69,496.
Certification in accordance with the Euro 6d standard (RDE stage 2) not prescribed for new models until 1 January 2020 is possible due to measures including extended exhaust gas aftertreatment with an additional underbody SCR catalytic converter including ammonia slip catalyst (ASC) in the underbody.
With this enhanced technology, NOx emissions drop to an average of 20 milligrams per kilometer in the case of the GLE 400 d 4MATIC, as shown by measurements in continuous operation of many thousands of kilometers. In individual journeys the values can also be considerably lower.
The GLE 400 d is the most powerful series-production diesel SUV ever offered by Mercedes-Benz. Most of the components relevant for efficient emissions reduction are installed directly on the engine.
The integrated technology approach combining the new stepped-bowl combustion process, dynamic multi-way exhaust gas recirculation and near-engine exhaust gas aftertreatment, combined for the first time with variable valve-lift control, makes further reduced consumption with low emissions possible.
With the near-engine insulated configuration, exhaust-gas aftertreatment does not suffer great levels of heat loss and generates extremely favorable operating conditions. The measures taken include high- and low-pressure exhaust gas recirculation including cooling, a diesel oxidation catalytic converter (DOC) to avoid the emission of carbon monoxide (CO) and unburned hydrocarbon (HC), a particulate filter with SCR catalytic function (sDPF), an SCR catalytic converter (selective catalytic reduction) for reducing nitrogen oxides. For this purpose, ammonia in the form of the carrier AdBlue is added to the exhaust gases before entering the sDPF.
The special features of the top-of-the-line engine in the premium diesel family include the stepped-bowl combustion process, two-stage turbocharging and, for the first time, the use of CAMTRONIC variable valve-lift control.
The stepped bowl has a positive effect on the combustion process, the thermal loading of critical areas of the pistons and the introduction of soot into the engine oil. The efficiency is increased by the higher burning rate in comparison with the previous omega combustion bowl.
The characteristic feature of the specifically configured combination of bowl shape, air movement and injector is its very efficient utilization of air, which allows operation with very high air surplus. This means that particulate emissions can be reduced to an especially low level.
Its design is characterized by the combination of an aluminum engine block and steel pistons, as well as the further improved NANOSLIDE coating of the cylinder walls.
The lower expansion of steel as operating temperatures rise ensures an increasing clearance between piston and aluminum block, thereby reducing the friction by 40 to 50 percent. At the same time, the fact that steel is stronger than aluminum allows very compact, lightweight pistons that even offer additional strength reserves. Finally, the lower thermal conductivity of steel leads to higher component temperatures, thereby improving the thermodynamic efficiency, increasing combustibility and reducing combustion duration.
The combination of innovative steel pistons and the optimized piston ring package with the NANOSLIDE coating of the cylinder walls results in benefits in terms of fuel consumption and CO2 emissions, especially in the lower and medium engine-speed ranges, which are of relevance for day-to-day vehicle use.