The ultra-modern 3.5-litre V6 engine of the S 350 L BlueEFFICIENCY is naturally aspirated, but also suitable for the future use of a turbocharger thanks to the modular design concept. The most striking change between the new V6 unit and its predecessor is a reduction in the V-angle between the cylinder banks from 90 degrees to 60 degrees. This enables the primary balancer shaft to be omitted, and as a result the driver registers an outstanding level of comfort.

The design highlights of the 3.5-litre V6 include a completely new air intake and exhaust system in conjunction with a variable resonance intake manifold and optimised inflow and outflow. Result: with the same displacement, the output compared with the previous 200 kW (272 hp) model is increased by 12.5 percent to 225 kW (306 hp), while maximum torque has increased by 5.7 percent to 370 Newton metres (predecessor: 350 Nm) and now is available over a broad engine speed range from 3500 to 5250 rpm.

In parallel with this substantial increase in power, Mercedes engineers have achieved an even more impressive reduction in fuel consumption. The predecessor's NEDC consumption was already good at 10.0 litres of premium petrol per 100 kilometres, but has now been cut by almost a quarter. The new V6 petrol engine in the S 350 L BlueEFFICIENCY is content with 7.6 litres per 100 kilometres. That adds up to savings of 2.4 litres or 24 percent, and makes the S 350 L BlueEFFICIENCY the most economical petrol model in the luxury class. CO2 emissions have also fallen by 23.5 percent to 179 grams per kilometre (long wheelbase). The S 350 L BlueEFFICIENCY combines excellent consumption figures with dynamic performance, accelerating from standstill to 100 km/h in 6.9 seconds. Top speed is 250 km/h (electronically limited).

The new V8 biturbo engine in the S 500 L BlueEFFICIENCY generates 320 kW (435 hp) with 15 percent less displacement (4663 cc instead of 5461 cc), and therefore around twelve percent more output than its 285 kW (388 hp) predecessor. Torque has risen from 530 to 700 newton metres – an increase of 32 percent.

Despite a considerable increase in power of 35 kW (47 hp), Mercedes developers have been able to reduce the combined fuel consumption of the S 500 L BlueEFFICIENCY significantly. At 9.3 litres of premium petrol per 100 kilometres, this is 16 percent (long wheelbase) below the figure for the preceding model. An outstanding figure in the luxury class, this corresponds to CO2 emissions of 219 grams per kilometre. The excellent efficiency goes hand in hand with superior performance: the S 500 L BlueEFFICIENCY sprints from zero to 100 km/h in impressive 5.0 seconds. Top speed is 250 km/h (electronically limited). The increase in output and torque despite the reduced displacement is mainly due to the use of two turbochargers – one for each bank of cylinders. These force the intake air into the eight combustion chambers at a pressure of up to 0.9. The turbochargers are configured to provide a high torque at low engine speeds, and an outstanding 600 newton metres are already available between 1600 and 4750 rpm.