The new four-cylinder diesel engine generation 

Leading the way in terms of power output, 
consumption and emissions

•	Two-stage turbocharging for high power output and spontaneous 
response
•	Fourth-generation common-rail technology
•	Technical innovations reduce consumption and emissions

The basic character of the new four-cylinder diesel generation from Mercedes-Benz can be described in just a few superlatives: greater power, greater economy, greater cleanliness. The new power unit from the Untertürkheim plant needs to be explained at greater length to be fully appreciated, however. It really does charter territory from which diesel engines – and particularly four-cylinder units – have previously been excluded. It redefines standards for power output and torque on the one hand and for fuel consumption and exhaust emissions on the other, setting benchmark figures which no other comparable series-production engine is able to match at the current time. 

The technical advance which the design engineers at Mercedes-Benz have achieved with this new four-cylinder diesel is not only evident on paper, its effects can also be experienced to an intense degree behind the wheel. As far as the figures are concerned, the most powerful variant of the new diesel engine extracts 150 kW/204 hp from its displacement of 2143 cubic centimetres. The power-to-displacement and torque-to-displacement ratios of the new engine are just as 
impressive, with figures of 70 kW/95.2 hp and 233.3 Nm per litre respectively.

Lower fuel consumption despite substantial gain in output

The engineers also took care to ensure that the new diesel engine is a paragon of fuel efficiency. Despite the substantial power boost of 25 kW, the engine makes even more frugal use of diesel than its predecessor, which was itself a most 
modest consumer of fuel. This is immediately apparent from the fuel consumption figures for the new C 250 CDI BlueEFFICIENCY, in which the powerpack is 
making its world debut. When fitted in the C-Class, the new 150-kW unit burns just 5.1 litres of diesel per 100 kilometres (NEDC), 0.8 litres less than previously. The Mercedes-Benz engineers have also succeeded in further reducing the untreated engine emissions. The new four-cylinder diesel already meets the future EU5 emission standard. 

Innovative technologies without parallel

The exemplary figures achieved by the new engine for output and torque characteristics, economy, exhaust emissions and smoothness are the result of a whole raft of innovative technologies. The principal features of the new Mercedes diesel engine:

•	Two-stage turbocharging ensures high power output and optimum torque 
delivery.

•	Fourth-generation common-rail technology with a rail pressure that has been increased by 400 bar to 2000 bar, plus a new piezoelectric injector concept featuring direct injector needle control creates the ideal basis for more 
flexible injection timing, leading to smoother engine running, lower fuel 
consumption and reduced emissions.

•	The maximum ignition pressure of 200 bar also contributes to the high power-to-displacement ratio.

•	Both the oil-spray nozzles and the water pump are activated in accordance with requirements to save energy and therefore fuel. The oil pump's controllable design additionally reduces the oil flow rate – and therefore fuel 
consumption.

•	The camshaft drive is positioned at the rear in order to enhance running 
refinement and satisfy the exacting pedestrian protection requirements. 

•	The engine block is made of cast iron, the cylinder head of aluminium.

•	A two-part water jacket in the cylinder head ensures maximum cooling in 
the area of the combustion chamber plate; it is this that enables an ignition pressure of 200 bar and such a high power-to-displacement ratio.

•	The cast-iron cylinder barrels have been more finely honed than in the preceding model, helping to improve consumption.

•	To compensate for the second-order forces which are inherent to four-cylinder in-line engines there are two Lanchester balancer shafts at the bottom of the engine block running in low-friction roller bearings rather than conventional plain bearings.

•	The two-mass flywheel has been specifically designed for high engine torque at low engine speeds in order to isolate the crankshaft's vibration stimuli, thereby contributing to the engine's excellent smoothness.