Now powered by a 6 – liter turbocharged 3 – liter engine, the S500 is as powerful as the previous V7 4.7 liter twin turbo, and more reactive at low rpm thanks to its electric compressor, all for reduced fuel consumption, A quarter. The S400d and its 6-cylinder diesel-powered turbocharged dual-stage turbocharged engine (dual steer) is rather pleasant on the new S-Class. The acoustic level, and also, of course, that of the driving thanks to its inexhaustible torque at low engine speed, very useful for moving the 2 tons of this S-Class.
It is a small revolution for Mercedes, who, almost a quarter of a century after having abandoned it because of compactness, now returns to the architecture of the 6 cylinders in line, this time mainly for industrial reasons. The aim is to extend the sharing of machining tools and mechanical components to the 4, 6 and 8 cylinders constituting the new Mercedes family of engines. And who knows, maybe it will soon get rich from a new V12, that of the restylée S65 is still based on the block launched in the 90s.
Like BMW a few years ago, Mercedes designed its new family of engines around a 500 cm3 combustion chamber and a common cylinder spacing, in this case 90 mm, with a bore of 83 mm for the blocks Gasoline, 82 for diesel engines. These characteristics are shared by all the new engines 4, 6 (in line), and 8 cylinders (V) from the manufacturer to the star. In contrast, unlike BMW, Mercedes does not believe the 3-cylinder 1.5 l, considered too expensive to balance.
The 6-cylinder in-line 3 liters gasoline released by the S-Class is declined in two versions which differ only by the parameters of their electronic management. The S500 develops 435 hp and 520 Nm for the S500, while the S450, which will be marketed on the French market, is limited to 367 hp and 500 Nm. These figures are obtained thanks to a double supercharging, consisting of a conventional turbocharger and A centrifugal electric compressor supplied by Borg & Warner. The latter is powered by a 48V network, such as the water pump and the air conditioning compressor, which are also electric, which makes it possible to remove the accessory belt at the front of the engine in favor of compactness. This 48V network is powered by an electric machine developing 16 kW and 250 Nm acting as flywheel, Alternator and electric motor when the need arises, such as during an acceleration at very low speed. The energy is stored in a lithium-ion battery of 0.9 kWh (of which only 0.5 are used).
These S450 and 500 are therefore “mild hybrids” or light hybrids. Still for reasons of compactness – a 6-cylinder is long and high, which can cause problems for the pedestrian shock – the camshafts are driven by the back of the block via a cascade of gables, Of variable angular setting. On the other hand, a system called Camtronic by Mercedes – very close to Audi’s “Valvelift” – allows two different intake cam profiles to be chosen to reduce pump losses at low loads. The volumetric ratio is 10.5: 1.
In the case of 6-cylinder diesel engines, the return to on-line architecture is mainly motivated by the fact that, unlike a V6, it has the enormous advantage of clearing on the side of the engine, Of the latter, the space required for the bulky exhaust after-treatment system required by the new Euro 6c standard. On an automobile of the size and mass of a Class S, this includes at least a particulate filter, an oxidation catalyst, and a nitrogen oxide reduction catalyst, and it is essential that all these elements Installed in the immediate vicinity of the exhaust manifold to reach their operating temperature as quickly as possible during cold starts. Baptized OM656, This new block that begins its career under the hood of the S-Class will soon animate all the Mercedes with longitudinal mechanics. Like the 4-cylinder diesel recently released by the E-Class, it is made of aluminum and its pistons are made of steel to reduce its expansion, and thus the friction on the barrels of cylinders uncoated, but treated by plasma projection of iron. The supercharging is ensured by two turbochargers mounted in series, one small with variable geometry, and one with fixed geometry. The main innovation here is the Camtronic exhaust system. Used in particular during cold starts, one of the two cam profiles makes it possible to re – aspirate some of the exhaust gases, Exhaust catalyst to increase the temperature and initiate more rapidly the operation of the SCR catalyst responsible for reducing nitrogen oxides. It is thanks to this system that Mercedes can afford to avoid the use of a NOx trap like that of the large diesel engines of its competitors VW and BMW. This new 6-cylinder 3.0-liter turbo diesel is available in two power levels, 286 hp and 600 Nm for the S350d, 340 hp and 700 Nm for the S400d, compared to the previous S350d’s 3-liter V6 3-liter V6.
In addition, a 4-cylinder 2-liter turbocharged direct gasoline engine developing about 270 hp should also soon appear under the hood of the Mercedes S-Class, but a priori it will be reserved for the Chinese market. Like the 6-cylinder he drives, he uses a Camtronic distribution with two cam profiles at the intake. It will also be able to receive the reinforcement of a starter alternator operating at 48V, but this one will then be connected to the crankshaft by a belt. It should also be noted that a V6 will remain in the Class S range for the future rechargeable hybrid version, the mechanics of which will be an evolution from that of the previous S500 PHEV, but with an electric range extended to more than 50 kilometers.
Finally, Mercedes took the opportunity to present a new generation of V8 deriving from the 4-liter twin-turbo AMG. For this block of 476 hp which animates the S560, the innovation lies mainly in the deactivation of cylinders. Again, the Camtronic system makes it possible to choose between two cam profiles. The idea here is to completely deactivate the valves of 4 of the 8 cylinders at low load and 900 to 3250 rpm. The result is that when the driver only slightly depresses the accelerator pedal, the displacement of the engine is halved, which makes it possible to drastically reduce pump losses and therefore fuel consumption.
Inside, the Mercedes S-Class impresses with its two 12.3-inch screens placed side by side under the same glass shield, creating a dramatic continuity effect between instrument cluster and center console. The main changes concern the steering wheel 3 branches, in our opinion much more pleasant to look than the one with 2 branches that it replaces. On the other hand, its tactile keys on which the driver must slide his thumbs laterally or vertically to scroll the menus are sometimes difficult to operate in the heat of the action, at least during such a short hold . Mercedes also focuses on extended voice control to act on air conditioning, lighting, seating and head-up display. Finally, A new “energizing comfort” function offers 6 programs combining ventilation, perfume, heating and massage by the seats, light and musical atmosphere to increase the well-being of the occupants. An entire program…
The S-Class remains THE reference from which all manufacturers venture into the luxury limousine segment. In fact, the levels of finish and comfort still represent today the best of the category. On the dynamic side however, if the S-Class remains at an excellent level, it can not compete with its competitors with 4 wheel steering at the same time more agile on winding roads and more stable at high speed, like the BMW 7 Series or The Porsche Panamera, waiting to see what party the future Audi A8 will draw from this technology. The latter also aims to establish a new reference in terms of comfort thanks to an active electromechanical suspension of a new principle and, on paper,
Another area in which the S-Class remains the reference, is soundproofing. But we would almost regret it, as for trying a new 6-cylinder in-line, whose characteristic song is hardly noticeable when it comes to the S450. However, its vigor is quite convincing, and this from the lowest rpm thanks to its electric compressor, whose conventional turbocharger takes over from 2500 rpm. The lightweight hybridization allowed by the electric machine replacing the flywheel also allows a stop & start function that is perfectly silent and free from vibrations. On the other hand, the regenerative braking system used to transform part of the kinetic energy into electricity disturbs the modulation of decelerations at very low speed.
The S400d’s 6-cylinder diesel, even more powerful at low rpm, not only offers better revivals, it also takes advantage of the 9-speed automatic transmission, which, in turn, must less often demote inadvertently, to the advantage Of driving fluidity. A real success. However, we will not say as much of the functions grouped under the name “intelligent drive”. Again, and as with most models equipped with driving aids tending towards the autonomous car, we have not found this arsenal convincing. Certainly it automatically keeps the car at a reasonable distance from the one that precedes it, and in its track, and can even now change it alone, under the action of the flashing. But this sophisticated system can, at any moment, Sponge for example in the event of a sharp turn or if the marking on the ground is no longer sufficiently visible by the camera, which implies that it must be constantly monitored by the driver (who thus finds himself paradoxically in the service of the system) . However, for the time being, it remains a legal and legal obligation under the current law …