State-of-the-art engine technology from the inventor of the diesel passenger car

The 2.2-litre CDI engine turns the ML 250 BlueTEC 4MATIC into the most economical SUV in its class. With NEDC fuel consumption of 6.0 l/100 km, the model even outperforms any hybrid model currently offered by the competition. Despite the low fuel consumption figures, this Mercedes-Benz M-Class model boasts maximum torque of 500 Nm at 1600 rpm and rated output of 150 kW (204 hp) with outstanding performance: the M-Class accelerates from 0 to 100 km/h in 9.0 seconds before going on to a top speed of 210 km/h.

Two-stage turbocharging produces high torque even at low engine speeds. The compressor package - already fitted in the compact SUV GLK 250 CDI 4MATIC - made up of a small high pressure (HP) and a large low pressure (LP) turbocharger contributes decisively to the high output on a par with the 6 cylinder unit in the predecessor model ML 300 CDI BlueEFFICIENCY 4MATIC. The two turbochargers are connected in series, and each has a turbine and a compressor driven by this turbine. The HP turbine is located directly at the exhaust manifold and initially allows exhaust gas to flow through it; it then rotates at up to 215,000 revolutions per minute. The HP turbine housing features an integral bypass duct, which can be opened or closed by means of a charge-pressure control flap. If the flap is closed, the whole exhaust stream flows through the HP turbine, so that the exhaust-gas energy is available solely for the HP turbine drive. This means that the optimum charge pressure can be built up at low engine revs.

The two compressors are likewise connected in series, and are in addition connected to a bypass duct. The combustion air from the air filter first flows through the low-pressure compressor, where it is compressed as a function of the LP turbine's output. This pre-compressed air then passes into the high-pressure compressor, which is coupled to the HP turbine, where it undergoes further compression. The result is a genuine two-stage turbocharging process. The major advantage of this sophisticated, demand-related control of the combustion air supply using two turbochargers is improved cylinder charging, and therefore high torque even at low engine speeds. Fuel consumption is also reduced. When the car is driven, this concept makes itself felt by harmonious driving characteristics with no turbo-lag, a favourable torque curve across the entire engine speed range, instant responsiveness and excellent performance.

The V6 diesel engine in the ML 350 BlueTEC 4MATIC guarantees effortlessly superior traction. It develops 190 kW (258 hp) and impressive torque of 620 Nm. Despite its extraordinary performance this version boasts combined NEDC fuel consumption of 6.8 litres of diesel per 100 kilometres. The highly efficient V6 diesel unit delivers effortlessly superior performance: the ML 350 BlueTEC 4MATIC accelerates from standstill to 100 km/h in 7.4 seconds before moving on to a top speed of 224 km/h. While delivering performance on a par with the predecessor model, the ML 450 CDI 4MATIC with V8 diesel engine, the new unit, however, boasts 36 percent lower fuel consumption.

Just like the ML 250 BlueTEC 4MATIC, the ML 350 BlueTEC 4MATIC also ranks among the world's cleanest diesel models: BlueTEC is a technology developed by Mercedes-Benz to reduce emissions from diesel vehicles, especially nitrogen oxides. AdBlue, an aqueous urea solution is injected into the exhaust gas stream as part of this process, releasing ammonia, which reduces up to 80 percent of the nitrogen oxides into harmless nitrogen and water in the downstream SCR (Selective Catalytic Reduction) catalytic converter. Upshot: both models already comply with the EU6 exhaust emissions standard due to be implemented in 2014. The AdBlue tank is located under the luggage compartment floor to protect it in the event of a crash, has a capacity of 25.7 litres and is topped up every 25,000 kilometres at the regular service intervals. The filler opening is located behind the side fuel filler flap alongside the tank filler neck and is marked clearly with a luminous blue cap. This configuration allows the ML driver to top up the tank easily if they take full advantage of the off-road capabilities of the M-Class and are unable to find a service station off the beaten track. AdBlue is available as a refill container from any Mercedes-Benz dealership; the instrument cluster provides a timely indication of the need to top up the tank.

Latest-generation BlueDIRECT direct-injection engine for the ML 350 4MATIC BlueEFFICIENCY

The ML 350 4MATIC BlueEFFICIENCY petrol-engined model features the groundbreaking technology of the new generation of V engines from Mercedes-Benz. At the heart of the BlueDIRECT technology package lies the enhanced third-generation spray-guided direct petrol engine with piezo-electric injectors. In combination with multi-spark ignition, this technology offers further possibilities for fuel savings.

The V6 engine in the ML 350 4MATIC BlueEFFICIENCY utilises a new stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology ("homogeneous stratified mode"). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual "stratified" injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.

The third-generation direct-injection system also features rapid multi-spark ignition (MSI). How it works: following the first spark discharge and a brief combustion period, the coil is rapidly recharged and a further spark is discharged. The MSI system enables up to four sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition. Controlling this rapid multi-spark ignition enables both the time lapse before the next spark and the combustion duration for the relevant operating point to be optimally adjusted. This provides scope for optimising the centre of combustion and improving residual gas compatibility, especially during stratified charge operation.

The ultra-modern 3.5-litre V6 unit has been designed as a naturally aspirated engine. As a major distinction from the preceding engine in the ML 350 4MATIC, the V-angle between the cylinder banks has been reduced from 90 degrees to 60 degrees. This has enabled the balancer shaft compensating primary vibrations to be omitted. As a result the driver notices an outstanding level of comfort. The design highlights of the 3.5-litre V6 include a completely new air intake and exhaust system in conjunction with a variable resonance intake manifold and optimised inflow and outflow. Result: with the same displacement, the output compared with the previous 200 kW (272 hp) model is increased by 12.5 percent to 225 kW (306 hp), while maximum torque has increased by 5.7 percent to 370 Nm (predecessor: 350 Nm) and now is available over a broader engine speed range from 3500 to 5250 rpm. In parallel with this substantial increase in power, Mercedes engineers have achieved an equally impressive reduction in fuel consumption. The predecessor's NEDC fuel consumption has been reduced by 25 percent. The new V6 petrol engine in the ML 350 4MATIC BlueEFFICIENCY consumes 8.5 litres per 100 kilometres, making it the most economical petrol model in its class. The model combines excellent consumption figures with dynamic performance, accelerating from standstill to 100 km/h in 7.6 seconds, and with a top speed of 240 km/h.

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