by Adrian Dorofte and Adrian Andronic
e-mail: mercedesbenzblog@gmail.com

The all new Mercedes-Benz CLS Shooting Brake: The drive system - Powerful and efficient

Common hallmarks of all five of the engines deployed in the Mercedes-Benz CLS Shooting Brake are superlative efficiency and the ultimate in driving enjoyment. The two diesel drives and three petrol engines also all feature a 7-speed automatic transmission and the ECO start/stop function. Two models with all-wheel drive are additionally available: CLS 350 CDI 4MATIC BlueEFFICIENCY and CLS 500 4MATIC BlueEFFICIENCY. Absolute peak performance is embodied by the CLS 63 AMG Shooting Brake.

The entry-level model is the CLS 250 CDI BlueEFFICIENCY with a power output of 150 kW (204 hp). Fuel consumption in combined mode is outstanding for this power category, at 5.3 litres of diesel per 100 kilometres, corresponding to CO2 emissions of 130 grams per kilometre. On the next level come the two six-cylinder engines: the CLS 350 CDI BlueEFFICIENCY rated at 195 kW (265 hp) and the CLS 350 BlueEFFICIENCY with a power output of 225 kW (306 hp). The V8 biturbo engine of the CLS 500 BlueEFFICIENCY generates an output of 300 kW (408 hp). The top model is the CLS 63 AMG, delivering up to 410 kW (557 hp).

An all-rounder: the four-cylinder diesel engine of the CLS 250 CDI

From the S-Class through the M-Class to the C-Class, the top version of the four-cylinder direct-injection engine measures up on all fronts while setting efficiency benchmarks in the luxury segment. In the second generation of the four-door Coupé it is being offered in this segment for the first time, as the CLS 250 CDI BlueEFFICIENCY. With an output of 150 kW (204 hp), a top speed of 235 km/h and a full 500 Nm of torque, it offers unbridled driving enjoyment while surprising the driver at the filling station with fuel consumption on a par with that of a compact car: on average, the CLS Shooting Brake gets by on 5.3 litres per 100 km, corresponding to CO2 emissions of 139 g/km.

The ultimate diesel: the V6 engine of the CLS 350 CDI

195 kW(265 hp) and 620 Newton metres of torque: The large diesel engine in the CLS 350 CDI BlueEFFICIENCY is a highly refined power house. Its performance figures are suitably impressive: the Shooting Brake accelerates to 100 km/h from a standing start in 6.6 seconds, and the top speed is 250 km/h. Ample tractive power and sporty performance are accompanied by exemplary fuel efficiency: in combined mode, the V6 runs on 6.0 litres per 100 km, while CO2 emissions stand at 159 g/km.

The Mercedes engineers carried out a thorough overhaul of the engine for the launch of the CLS Coupé. It now has improved engine management in the form of new-generation control units and new software, new sensors and actuators, and more efficient aftertreatment in the maintenance-free diesel particulate filter system with reduced back-pressure. In addition to more effective cooling of recirculated exhaust gas using a variable bypass valve, the in-engine measures include a reduction of the compression ratio from 17.7:1 to 15.5:1, an optimised VNT turbocharger with low-friction shaft bearings for greater agility and high output, new injection nozzles and revised ducting in the intake tract. A whole package of measures has resulted in substantial fuel savings: apart from the ECO start/stop function, these also include generally lower in-engine friction (through precision honing of the cylinder walls, amongst other measures), more efficient thermal management, an improved compound oil pump and modified cylinder head cooling.

The V6 diesel engine is also deployed in the CLS 350 CDI BlueEFFICIENCY 4MATIC.

Petrol engine with BlueDIRECT: the most efficient form of direct injection

The second generation of direct petrol injection made its debut in the CLS 350 CGI introduced in 2006. The six cylinder unit was the world's first petrol engine with piezo-electric direct injection and spray-guided combustion, and as such achieved a fuel saving of around ten percent compared with its predecessor with port injection.

The current CLS features third-generation direct petrol injection. The innovation which goes by the name of BlueDIRECT has established the V-engines from Mercedes-Benz as worldwide benchmarks, both by virtue of their elegantly powerful thrust and in terms of fuel consumption. Key data for the CLS 350 BlueEFFICIENCY: 225 kW (306 hp), 370 Nm, 7.3 litres of fuel per 100 km, 169 g CO2 per km. The CLS 350 BlueEFFICIENCY accelerates from zero to 100 km/h in 6.7 seconds and attains a top speed of 250 km/h.

Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, disposes of a system pressure of up to 200 bar as the third-generation BlueDIRECT injection system, with variable optimisation of the pressure level according to the engine's characteristic map. Piezo-electric injectors allow up to five injections per power stroke for the best possible mixture formation, while multi-spark ignition helps to ensure reliable combustion of the mixture. Key features of the V6 petrol engine with BlueDIRECT technology in the CLS 350 BlueEFFICIENCY are:

- 60° cylinder angle, no balancer shaft

- Extended lean-burn operation, lean-burn system with load monitoring from pressure information, new combustion system operating modes

- Multi-spark ignition

- Resonance intake manifold

- Latest generation of piezo injectors

- Enhanced cooling circuit control and optimisation

- Enhanced oil circuit control and optimisation

- Increased output and torque


V8 biturbo: the ultimate in refined sportiness

While V6 is a naturally aspirated engine, the technically closely related V8 engine in the CLS 500 BlueEFFICIENCY features biturbo-charging. The V8 also disposes of direct injection, but it has been designed for countries in which sulphur-free fuel is not available and is thus operated in homogeneous mode throughout the entire performance map. With a cubic capacity of 4633 cc, the eight-cylinder engine delivers 300 kW (408 hp) of power and maximum torque of 600 Nm. This enables the CLS Shooting Brake to accelerate from 0 to 100 km/h in 5.3 seconds while maintaining exemplary fuel efficiency for its power category at 9.2 l/100 km, corresponding to CO2 emissions of (214 g/km). The V8 biturbo is also available as a CLS 500 BlueEFFICIENCY 4MATIC variant.

CLS 63 AMG: delivering up to 410 kW (557 hp)

The AMG 5.5-litre V8 biturbo engine impresses with a combination of direct petrol injection with spray-guided combustion, piezo injectors, biturbocharging, air/water intercooling, generator management and ECO start/stop function.

The eight-cylinder engine is the embodiment of pure dynamism and high efficiency: offering power output and torque levels of 386 kW (525 hp) and 700 Nm respectively, the effortless superiority of the CLS 63 AMG Shooting Brake can be enjoyed by the driver over every single kilometre. In conjunction with the "Edition 1", these figures are pushed to 410 kW (557 hp) and 800 Newton metres. Both variants offer driving performance of the highest calibre: accelerating from zero to 100 km/h takes 4.4 and 4.3 seconds respectively, and the top speed is 250 km/h (electronically limited).

Overview of the engine programme for the CLS Shooting Brake (figures for 4MATIC versions in round brackets, for CLS 63 AMG "Edition 1" in square brackets):

7G-TRONIC PLUS automatic transmission also available with the four-cylinder diesel engine

All CLS models apart from the CLS 63 AMG come with the 7G-TRONIC PLUS automatic transmission as standard. The current generation of the torque converter provides an improved dynamic response, better durability and reduced noise and vibration levels thanks to a new hydraulic circuit, as well as enhanced dampers and torque converter housing. The extreme wheel-slip reduction of the torque converter housing, combined with larger mechanical damper de-coupling, helps to reduce consumption significantly. In addition, the gearshift program in ECO mode has been changed in favour of lower engine rpm at cruising speeds.

AMG SPEEDSHIFT MCT 7-speed sports transmission – individual and flexible

The CLS 63 AMG Shooting Brake is fitted with the AMG SPEEDSHIFT MCT 7-speed sports transmission. Equipped with four individual transmission modes as well as automatic double declutching and RACE START functions, its power delivery is characterised by responsiveness and maximum variability. In "Controlled Efficiency" (C) mode, the ECO start/stop function is always enabled and switches the eight-cylinder engine off when the vehicle is at a standstill. In "S" (Sport), "S+" (Sport plus) and "M" (Manual) transmission modes, the engine and transmission are significantly more responsive: short, precisely defined interruptions of ignition and injection result in faster gear changes under full load.

4MATIC all-wheel drive: superior traction, whatever the conditions

The all-wheel drive is designed as a permanently operative drive mechanism. This offers crucial advantages over other systems, which activate all-wheel mode only after detecting a lack of traction. In contrast, the 4MATIC transfers drive torque via the wheels to the road without any interruption. In addition, the Shooting Brake offers quiet running and vibrational comfort in line with the high standards expected of vehicles from Mercedes-Benz.

When pulling away in slippery conditions, the 4MATIC models are designed

to develop maximum traction. To this end, certain road conditions are automatically detected and the interventions of the 4ETS electronic traction control system adjusted so as to achieve the greatest possible acceleration while minimising wheel slip, ensuring optimum directional stability in the process. This strategy also allows the vehicle to pull away under the most adverse conditions, such as when one side of the vehicle is on an icy slope (µ-split) or both wheels on either the front or rear axle have limited grip (µ-jump).

On twisting roads covered with snow and ice, driving stability is primarily controlled by the ASR acceleration skid control system's regulation of engine torque. The ASR control thresholds are adjusted according to the driving situation based on the vehicle's longitudinal and lateral dynamic readings as continuously measured by the ESP® sensor system. If vehicle stability is to be maintained, the longitudinal force when cornering must be controlled by means of engine torque regulation in such a way that there are sufficient reserves of lateral force at all times. In order to comply with this physical correlation, when cornering on road surfaces with a low friction coefficient the control thresholds for engine torque regulation at the wheels on the outside of the bend are reduced considerably so that the tyres can develop sufficient lateral force.

As with the system’s set-up on a dry or wet road, handling stability and subsequently active safety are paramount at all times when wintry conditions prevail too in the CLS models with 4MATIC. The mechanical principle of the 4MATIC system, featuring a 45:55 torque split between the front and rear axles and a multi-disc limited-slip centre differential with a basic locking torque of 50 Newton metres, offers all the right ingredients for this.

This basic design enables high levels of traction, as the dynamic shift in axle load toward the rear axle that occurs during acceleration is harnessed to deliver more drive torque to the rear wheels. However, the multi-disc differential lock is also able to shift the drive torque between the front and rear axles, varying the split between 30:70 and 70:30 as the road conditions dictate. Consequently, intervention by the ESP®, 4ETS or ASR electronic control systems can be delayed for as long as possible and the bulk of the drive torque converted into tractive power, even on slippery roads. All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving near the limit, as a yellow warning symbol will flash in the instrument cluster. This serves as a clear prompt to adapt the driving style to the road conditions.











Credits: Daimler AG

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