Road Test

Road Test: 2011 Mercedes-Benz S 250 CDI

July 11, 2011

MB S 250 CDI 2011_00I usually prefer a big sedan like the S-Class to be black, but apparently white exterior works quite nicely as well. Diamond White exterior with the 20″ Behes alloys make the big and luxurious S-Class sedan look a bit sportier. However, we haven’t come here to make a judgement on the car’s outlook, but to try it’s new engine, which sounds something completely else than a sporty. Now, for the first time in S-Class history there is a 4-cylinder engine available, and it’s a diesel.

The main reason for this new engine are obviously the consumption and emission figures. With smaller engine, it is possible to reach even smaller fuel consumption. And so it does. The avarage fuel consumption is just 5,7 litres per 100 kilometres and the CO2 emissions are 149 g/km, which sounds incredibly small number for a car this big. On the road the car seems to be as economical as the manufacturer has promised. On the highway, with a driving speed of 80-100 km/h the consumption is around 5,0 litres per 100 kilometres and on the motorway (120-130 km/h) the consumption rises a bit, but is still well under 6,0 litres. In the city the ECO start/stop function helps to keep the fuel consumption low by switching the the engine off as soon as the vehicle stops – for example at traffic lights. The engine restarts immediately when the driver takes his foot from the brake pedal.

So, the 4-cylinder S-Class sure is economical to drive, but how about the performance. There is no point of buying the S-Class if it’s underpowered. Related to this, I have to reveal one more bad thing about this engine, before we get to the good part. It says 250 CDI, but the engine’s displacement is actually just 2143cc. So we have a 2.2-litre diesel engine in the S-Class. It sounds bad, but actually this small engine is quite marvelous. It produces 204 horsepower and mighty 500 Newton metres of torque. And the best part is that the best torque is available on very low revs at just 1600-1800rpm. This high torque at low engine speeds is a result of two-stage turbocharging. The compact module for the two-stage turbocharger consists of a small high-pressure (HP) turbocharger and a large low-pressure (LP) turbocharger. These are connected in series, and each has a turbine and a compressor driven by this turbine. The HP turbine is located directly at the exhaust manifold and initially allows exhaust gas to flow through it. It then rotates at up to 215,000 revolutions per minute.

The S 250 CDI accelerates quite nicely from low speeds with low engine revs, when you have a lot of torque available. But when accelerating from higher speed, for example when overtaking, that’s when you could use a bit more power. According to the official numbers, the S 250 CDI can speed up from zero to 100 km/h in 8.2 seconds and reach a top speed of 240 km/h. So nothing spectacular, but good enough to keep you going with the traffic. We were quite sceptical about this 4-cylinder engine at the start, but it gives surprisingly good performance considering how economical it can be. It might not be the right choice for all the S-Class buyers, but for those looking for economical version of this luxury car, the S 250 CDI is definitely worth of consideration.



  • Diesel
  • 4-cylinder
  • 2143cc
  • Turbo


  • 150 kW (204 hp) / 4200rpm


  • 500 Nm / 1600-1800rpm


  • 7-speed automatic
  • RWD

0-100km/h / 0-62mph

  • 8.2 seconds

Top speed

  • 240 km/h

Fuel consumption

  • 5.7 l/100km

CO2 emissions

  • 149 g/km

MB S 250 CDI 2011_05