Mercedes-Benz – The Drive System


Four new engines giving the ultimate in driving pleasure

  • Petrol engines: Direct-injection reduces consumption by 25% in the V6
  • Refined: ECO start/stop function for reduced consumption in urban traffic
  • All engines come with enhanced 7G-TRONIC PLUS automatic transmission

Mercedes Benz CLS 350 Drive

Efficiency at the highest level: this is the common characteristic shared by the engines used in the Mercedes-Benz CLS. Both of the engines feature increased performance and torque compared with previous models, while at the same time boasting significantly reduced consumption and CO2 emission levels.

Thanks to third-generation direct injection technology, the V6 petrol engine in the CLS 350 BlueEFFICIENCY is 25 percent more economical than before, despite an increase in maximum output of 10 kW: it now consumes just 6.8 litres per 100 km.

In terms of CO2 emissions at 161 g/100 km, this figure makes theV6 variant a global role model in its performance class. Advances in efficiency which are every bit as impressive are also to be expected of the V8 engine. The CLS 500 BlueEFFICIENCY has a power output of 300 kW and a torque of 600 Nm, and CO2 emissions of 209 g/km.

In addition to optimisations in the powertrain – the CLS models are fitted with the enhanced 7G-TRONIC PLUS automatic transmission and the sophisticated ECO start/stop system that helps to ensure extreme efficiency even when driving in urban traffic, as a standard feature.

Petrol engine with the most efficient form of direct injection technology

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.

Now the third generation of direct petrol injection is also featured in the new CLS. This direct injection technology is helping to establish the V-engines of Mercedes-Benz as the world benchmark, enabling a further reduction of 20 percent in fuel consumption to be achieved solely through in-engine measures.

The key data of the CLS 350 BlueEFFICIENCY include: 225 kW (plus 10 kW), 370 Nm (plus 5 Nm), fuel consumption of 6.8 litres per 100 km (minus 2.3 litres). The CLS 350 BlueEFFICIENCY accelerates from 0 to 100 km/h in 6.1 seconds, and achieves a top speed of 250 km/h.

The V6 petrol engine with direct injection technology in the CLS 350 BlueEFFICIENCY differs from its predecessor in the following key areas:

  • 60° cylinder angle and omission of 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

Third-generation direct injection technology

Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further by the engineers into third-generation direct petrol injection with spray-guided combustion.

The system pressure is now up to 200 bar and is variably optimised according to the engine’s characteristic map.

Completely newly developed 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. Further details on direct injection can be found in the section “Under the microscope: lean-burn mixture”.

While the V6 unit is a naturally-aspirated engine, the new, technically similar V8 engine, which is due to be introduced during 2011 as the CLS 500 BlueEFFICIENCY, features biturbocharging for the first time, previously only seen in the 12-cylinder engine used in the S-Class.

It too has direct injection but was designed for countries without sulphur-free fuel and is therefore run in a homogenous mode through the engine’s entire characteristic map. Despite a significantly smaller displacement (4633 cc; previously 5461 cc), the eight-cylinder unit made considerable gains in terms of output (300 kW; previously 285 kW) and torque (600 Nm; previously 530 Nm).

At the same time consumption has been significantly reduced. It is expected to achieve a saving in the region of 25 percent. Further details on the new engine generation can be found in the section “Under the microscope: innovative engine technology”.

The petrol engines of the new CLS at a glance

Cylinder arrangement/ number V6 V8
Displacement [cc] 3498 4633
Rated output [kW at [r/min] 225 / 6500 300 / 5250
Rated torque [Nm] at [r/min] 370
3500 – 5250
1800 – 3500
Fuel consumption
[l/100 km] 6.8 ≤9.0*
CO2 emissions
[g/km] 161 ≤209*

provisional figures

ECO start/stop function: significantly reduced consumption in urban traffic

When the car is at a standstill, the engine does not need to be running and therefore does not need to consume fuel. Recognition of this essentially simple fact is behind the ECO start/stop function, which is available for the first time in the CLS with the 7G-TRONIC PLUS automatic transmission.

In order to implement the auto start and auto stop function with a very high level of comfort in a Mercedes-Benz, it has been necessary to develop complex control logistics and a series of new or modified components, such as a Hall sensor for the crankshaft and a high-output starter motor.

That’s because Mercedes drivers should only really notice the forced breaks taken by the engine when they are at the filling station – thanks to consumption figures which are up to eight percent lower in urban traffic and five percent lower in the ECE consumption cycle. In the case of the CLS 350 BlueEFFICIENCY and CLS 500 BlueEFFICIENCY models, the ECO start/stop system is fitted as standard. (More details can be found in the section “Under the microscope: ECO start/stop function”.)

  • The 80-litre tank comes as standard on all CLS variants.
  • 7G-TRONIC PLUS automatic transmission standard

All CLS models come with the 7G-TRONIC PLUS automatic transmission as standard, for which the torque converter and main transmission have been developed and improved further with regard to fuel consumption and comfort.

The new 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 r/min at cruising speeds.

With friction-optimised bearings and gaskets, as well as a new automatic transmission oil (FE-ATF) with reduced viscosity combined with an enhanced additive package, the transmission itself also contributes towards reducing consumption.

When the cooling limits are observed, the increased service life of the new oil results in new oil change intervals of every 125,000 kilometres (new) instead of once every 50,000 kilometres (old). The improved electrohydraulic assembly of the transmission and the new friction-reducing materials used on certain transmission parts, combined with optimised software, also lead to better shift quality.