195 kW (265 hp) and 620 Nm of torque: the excellent diesel engine in the CLS 350 CDI BlueEFFICIENCY is now even more powerful and boasts a correspondingly superior performance. The Coupé accelerates to 100 km/h in 6.2 seconds, and has a top speed of 250 km/h. And despite the increase in output of 30 kW and the additional tractive power of 80 Nm, the V6 consumes a fifth less fuel than previously, at 6.0 litres per 100 km.

To achieve this, the Mercedes engineers have basically revised the engine. 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: these 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. With an engine idling speed of 520 rpm, a new optimum value has also been achieved.