Mercedes-Benz is introducing a newly developed four-cylinder gasoline engine that delivers the performance of a high-capacity six-cylinder engine but with significantly reduced fuel consumption for the E‑Class Coupé and Cabriolet.
The engine generates 220 kW/299 hp from a displacement of 1991 cc. In the E 350 Coupé if achieves fuel consumption (combined) of 6.7 l/100 km (35 mpg US) with combined CO2 emissions of 149 g/km); in the E 350 Cabriolet, its fuel consumption (combined) is 6.8 l/100 km (34.6 mpg US) with combined CO2 emissions of 154 g/km. Technologies such as the EQ-Boost starter-Generator, 48 volt on-board electrical system and a gasoline particulate filter (GPF) contribute to enhanced environmental compatibility.
The engine’s special features include twin-scroll turbochargers, belt-driven 48 V starter-alternator (EQ Boost) and electric 48 V water pump.
Twin-scroll turbo. Unlike conventional systems, a twin-scroll turbocharger merges the exhaust gas ducts of cylinder pairs in the flow-optimized manifold. This turbocharging concept with systematic cylinder flow separation produces high torque in the low rpm range together with high specific output.
A further-improved intake manifold with extremely short air paths and an exceptionally compact compressor housing additionally ensure spontaneous engine response and a fast reaction to accelerator pedal movements. The twin-scroll turbocharger has an electric wastegate actuator, which allows fast changes of the charge-air pressure.
To reduce exhaust emissions, use is made of tried-and-tested piezo injectors with a good mixture preparation, a further-improved combustion chamber and a particulate filter for petrol engines. Further efficiency measures include intake CAMTRONIC and a friction loss reduction package.
In conjunction with the modern on-board 48 V technology, the starter-alternator enables increased efficiency by making hybrid functions available.
|Key technical data|
|No. of cylinders/arrangement||4/in-line|
|Displacement per cylinder, cc||498|
|Total displacement, cc||1991|
|Cylinder spacing mm||90|
|Connecting rod length mm||138.7|
|Rated output, kW/hp||220 /299 at 5800-6100 rpm|
+10 kW via EQ Boost starter-alternator
|Peak torque, N·m||400 at 3000-4000 rpm|
48 V electrical system and starter-alternator enable hybrid functions. In the E-Class Coupé and Cabriolet, the new gasoline engine is combined with a 48 V electrical system, which is used for the belt-driven starter-alternator (EQ Boost) and the electric water pump. Fundamental advantages of a 48 V on-board electrical system include offering four times the power of a 12 V system at identical currents, but avoids the additional safety architecture of a high-voltage electrical system.
Furthermore, in conjunction with the belt-driven starter-alternator, the 48 V on-board electrical system enables the key hybrid functions. These are seen in such features as easy start, in which the engine starts and accelerates almost imperceptibly; boost (this function can support the combustion engine in the engine speed range up to 2500 rpm with additional output of up to 10 kW and 150 Nm of torque from the electric motor); recuperation of up to 12 kW when braking; optimized engine operation range; and gliding with automatic engine switch-off when the driving conditions permit this.
The belt-driven starter-alternator is coupled with the internal combustion engine in a manner similar to how the alternator is commonly connected. The system therefore uses existing generator mounting points and does not interfere with the design of the powertrain. In addition, such a starter concept is so durable that the engine can be switched off much more often and whenever it is not needed: whether during decelerating or coasting, i.e. when rolling to save fuel at higher speeds, as soon as drivers take their foot off the accelerator.
Apart from reduced fuel consumption and CO2 emissions, the 48 V on-board electrical system also brings about increased comfort. This comes as a result of the 48 V on-board electrical system being able to crank the internal combustion engine to idle speed very smoothly. This benefits NVH (noise, vibration, harshness) and the transition when the engine starts is even quieter: the engine restarts as if it had never been off.
The integration of a 48 V on-board electrical system also offers advantages for further functions in the vehicle in future. With the higher voltage, the same power requires only a quarter of the current of a conventional system. This means that the wiring may be thinner and thus lighter—which indirectly contributes to saving fuel. The 48 V on-board electrical system also paves the way for the further expansion of infotainment and assistance systems.
The basic price for the new E 350 Coupé is €59,738 (US$70,200), and for the E 350 Cabriolet €65,212 (US$76,600) (incl. VAT in each case).