The Mercedes-Benz S250 CDI BlueEfficiency, to give its full name, will use a 2.2 litre twin-turbo diesel four-cylinder that is already seen in its C and E-Class siblings. The engine is capable of producing 224bhp and 500Nm of torque.

While there will be an obvious performance sacrifice, the S250 makes up for it by claiming a fuel consumption figure of 5.9 litres of diesel per 100km. The S250 is also only 11bhp away from the next S-Class in the range, the S350 CDI, which uses a V6 engine.

With the introduction of the new four-cylinder engine, Mercedes is said to be working on improving the performance of its existing six-cylinder powerplants, in a bid to expand the gap between the entry-level model and the main models in the range. Power output of the sixes is expected to grow to 285bhp, up from 235bhp currently. The eight-cylinder S450 CDI might also be phased out as a result.