by Adrian-Liviu Dorofte

The new Mercedes-Benz GLK 2012: Drive system - Efficient, clean, powerful

The modern range of engines in conjunction with the comprehensive BlueEFFICIENCY measures provides for drive comfort and attractive performance in all GLK models combined with low emissions and fuel consumption.

In all, there is a choice of six diesel models and one petrol engine. The GLK 250 BlueTEC 4MATIC boasts the most powerful four-cylinder diesel engine in the SUV world. The direct-injection engine rated at 150 kW (204 hp) and generating 500 Newton metres of torque from 2143 cc enables the GLK to perform superbly. Key merits are the engine's torquey character, its top speed and its flexibility. Despite its formidable performance, this model is extremely frugal when it comes to fuel consumption: on average, the compression-ignition engine consumes 6.1 to 6.5 litres of diesel per 100 kilometres (combined NEDC fuel consumption). CO2 emissions stand at 159-169 grams per kilometre. Similarly to the GLK 220 BlueTEC 4MATIC model, it also complies with the EU6 emissions standard and the US BIN‑ 5 standard.

The two rear-wheel drive models GLK 200 CDI BlueEFFICIENCY and GLK 220 CDI BlueEFFICIENCY with six-speed manual transmission are even more fuel‑efficient. Both versions get by on 5.5 - 5.6 litres of diesel per hundred kilometres (143 - 147 g CO2/km). The top performer among the diesel versions is the GLK 350 CDI 4MATIC BlueEFFICIENCY. 620 Newton metres of torque provide the V6 compression-ignition engine with exceptional power delivery from low revs. Despite the 25 kW/35 hp power increase, the top diesel model runs on around 17 percent less diesel fuel, at 6.9 – 7.0 litres per 100 kilometres (179-183 g CO2/km, NEDC combined mode).

The GLK 350 4MATIC BlueEFFICIENCY petrol-engine model makes its mark with the groundbreaking technology of the leading generation of V engines from Mercedes-Benz. At the heart of the BlueDIRECT technology package lies the third-generation spray-guided direct petrol engine with piezo injectors. In combination with multi-spark ignition, this technology offers further potential for fuel savings.

The key data at a glance:
BlueEFFICIENCY measures for further reductions in fuel consumption

The excellent fuel economy of all GLK models is underpinned by a comprehensive package of BlueEFFICIENCY measures as well as the state-of-the-art engine technology. In addition to the ECO start/stop function that comes as standard, these measures include the seven-speed 7G-TRONIC PLUS automatic transmission. Low-friction axle drives, electric steering and tyres with low rolling resistance also play their part in reducing fuel consumption.

7G-TRONIC PLUS, standard on all 4MATIC models of the GLK-Class, boasts even lower converter slip and optimised efficiency. A central role is played by the new torsion damper, which effectively eliminates torsional eccentricities and vibrations in the transmission. The lower the rpm and the lower the number of cylinders, the more severe these can be. This results in a conflict of aims between comfort and fuel-efficient operation. Mercedes-Benz developers resolved this by using what is known as a twin-turbine damper, which is also fitted with a centrifugal pendulum on the diesel models. Depending on the rpm, this moves the centre of mass and allows comfortable operation even in the most economical operating range. Furthermore, the optimised damping allows a marked reduction in the slip of the torque converter lockup clutch even under low loads, which also contributes to fuel savings. This technology also allows an even faster response to driver commands via the accelerator pedal. Friction-optimised bearings and new transmission oil thermal management also help reduce fuel consumption.

The standard-fit ECO display in the instrument cluster further enables the driver to check the effects of his driving style on fuel consumption, and to modify his driving behaviour as necessary. The ECO display visualises the fuel efficiency of the driver's style by means of three bar diagrams.
Moderate acceleration, steady driving and a foresighted, anticipatory style triggers a rise in the individual bars, which always stand at 50 percent when the vehicle is started up. Conversely, heavy acceleration, major variations in speed or frequent braking in relation to coasting down without braking cause the bar values to drop. Drivers who quickly fill the bars and keep them at 100 percent thus demonstrate a particularly energy-efficient style of driving.

4MATIC: powerful all-wheel drive with cutting-edge control systems

The 4MATIC drive system in the GLK-Class is among the most powerful all-wheel drive systems there is; its control systems break new ground. Advantages over other systems with a transversely installed drive unit are achieved thanks to the basic compact, light and friction-loss-optimised design with its longitudinally positioned engine and integrated main and transfer case. Fuel consumption, for example, is at the same level as that of a comparable, conventionally driven vehicle, whilst noise and vibration levels are on a par with those in higher vehicle categories.

In combination with the ESP®, ASR und 4ETS dynamic handling control systems, the basic 45 : 55 percent distribution of drive torque between front and rear axle provides for superior and clearly predictable handling. The newly developed multi-disc clutch in the central differential supports the system when particularly low friction values apply between tyres and road surface, such as on snow or ice. A basic locking effect of 50 Newton metres between front and rear axle results in a significant increase in traction while maintaining a high level of driving stability.

Credits: Daimler AG

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