Mercedes-Benz CLS 250 CDI BlueEfficiency Launched In SA

By SACarFan on 10 September, 2012 in Featured, New Models

Last week Mercedes-Benz introduced its 4-cylinder, turbocharged, diesel engine to the CLS range, in the form of the CLS 250 CDI BlueEfficiency. Mercedes-Benz’s highly efficient oil burner has 2 143 cc of displacement and two-stage turbocharging. It’s an engine that’s headlined the E-Class and C-Class BlueEfficiency ranges ever since the necessary technical tweaks were made to sidestep that perennial South African problem – poor diesel fuel quality.

In CLS 250 CDI guise, the engine produces exactly the same power and torque as the E250 CDI, that being 150 kW and a healthy 500 Nm of torque. In fact, the same engine does duty in the C220 CDI where it’s been detuned to 125 kW and 400 Nm. Performance and efficiency is almost identical between the three models, however, in the CLS it offers a sprint from 0 – 100 km/h in 7.5 seconds, a top speed of 240 km/h, average fuel consumption of 5.2 L/100km and emissions of 134 g/km CO2.

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For the first time since we can remember in a hi-tech diesel engine, Mercedes-Benz says they don’t restrict owners to use 50 ppm sulphur diesel. They say it is prefered, but in fact they encourage you to lob in some greasy, 500 ppm sulphur diesel every now and again, because it acts as a good lubricant for the engine.

To attain a smaller carbon foot print and help realise their new holistic approach to overall carbon emissions, Mercedes-Benz have used an exclusive ‘dry machining’ process during the construction of the BlueEfficiency CDI engine. The process reduces the amount of crude oil-based lubricants required in the machining of complex components, such as crankshafts or cylinder heads, thereby saving resources and lowering production emissions. In terms of the engine’s workings, dual stage turbocharging has been used to eliminate turbo lag through use of a small turbo at low engine revs, supported by a larger turbo at high revs to achieve strong performance. The turbochagers can spin at speeds of 248 000 r/min and 180 000 r/min respectively, speeds that Mercedes say are five times faster than any other production turbo.

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We think Mercedes-Benz have gone to town on the CLS’s twin-turbo, 4-cylinder engine and, as a result, it holds the title of the world’s most powerful 4-cylinder diesel engine to-date. The engine block is made from cast iron for extra strength, with the crank case and cylinder head being forged from aluminium for minimal frictional resistance. Fourth generation common-rail direct injection now sports a potential maximum rail pressure of 2 000 bar (up from 400 bar), with hi-tech Piezo-electric injectors that utilise ceramic crystals to optimise injection quantities to within a thousandth of a millimeter.

There are two Lancaster balancer shafts at the bottom of the engine block, which run in low-friction roller bearings to compensate for the free vibration moments inherent to 4-cylinder diesel engines. A dual-mass flywheel, with a mass fixed to the crankshaft and a secondary mass connected by springs to the transmission, serves to ensure further engine smoothness.

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Of course Mercedes-Benz don’t have it all their own way with high-powered, high-efficiency diesels. The BMW 520d and Jaguar XF 2.2 diesel are both equally impressive pieces of kit in the 4-cylinder diesel saloon market. The Mercedes-Benz CLS 250 CDI BlueEfficiency can rightly grab the headlines for just one hot minute. The engine is a rather fitting tribute to the 151st anniversary of the birth of diesel inventor Mr. Rudolf Diesel.