by Adrian-Liviu Dorofte

The new Mercedes-Benz E-Class 2013: Engines, drive system, chassis and suspension

I. Engine and drive system: Superior performance, economical consumption

"E" for "Efficiency": this is the well-proven success formula with which the E-Class is raising the bar and showing how the intelligent interaction between technical innovations throughout the drive train can reduce fuel consumption. 

The E-Class Saloon and Estate are available with a broad range of powerful and efficient petrol and diesel engines with optimised drive train. All are fitted with the ECO start/stop system.

The petrol engines: powerful, fast and clean

The BlueDIRECT petrol engines from Mercedes-Benz, which to date have comprised the familiar V6 and V8 engines, are characterised by the latest technology. A new addition is a six-cylinder engine which is being offered for the first time in the E-Class not only as a naturally aspirated engine, but also as the E 400 with a displacement reduced to three litres but also with a biturbo drive as a result. With its output potential and enormously high torque at low engine speeds, this six-cylinder model sets new standards in its segment. It produces 20 kW more compared with the E 350. Its torque has increased by 110 Nm and remains available in the engine speed range of 1600 to 4000 rpm. On top of this, the new, efficient six-cylinder engine also fulfils the EU6 emissions standard. The E 500 is making a name for itself as the most economical model in the V8 segment.

Another new addition to the BlueDIRECT petrol engine family is a four-cylinder petrol engine. With a combined fuel consumption in the E 250 of 5.8 litres (135 g CO2 per km) and producing 155 kW (211 hp) from a displacement of just two litres, as well as 350 Nm of torque across a wide range of 1200 to 4000 rpm, it sets new standards in the four-cylinder segment. Providing acceleration from 0 to 100 km/h in 7.4 s (Estate 7.8 s), it provides the E-Class with spirited performance.

Lean burn process with stratified charge operation

Depending on the operating conditions, the new four-cylinder engine features stratified charge or homogenous operation. With stratified charge operation, the high-compression engine runs with significant excess air. To achieve this, the fuel is only sprayed into the air, which has already been compressed by the pistons, during the compression phase. A precisely controlled electronic multiple injection system helps to ensure that a fuel/air cloud builds up in a limited area around the spark plug, precisely at the time of ignition. This lights the ignitable fuel/air mixture around the spark plug, whereas only a very lean mixture with high excess air is to be found in the remainder of the combustion chamber. This enables extremely efficient combustion.

A prerequisite for stratified charge operation is fast piezo injectors. They spray the fuel into the combustion chambers several times in succession per power stroke, and as such enable specific control of the mixture formation and thus the flammability.

The new four-cylinder petrol engine from Mercedes-Benz also sees the world's first use of this stratified lean burn process in combination with exhaust-gas turbocharging and external high-pressure exhaust gas recirculation. As a result the E 250 achieves a combined optimum consumption figure of 5.8 litres per 100 km (corresponding to 135 g of CO2/km), and is therefore the only vehicle in this segment to achieve efficiency class A. In addition, the new BlueDIRECT four-cylinder petrol engines already meet the EU6 emissions standard which will apply from 2015. The new four-cylinder engine also meets the EU6 emissions standard in the guise of the homogenous variant for countries with different fuel qualities.

Advanced technology makes engines more efficient

The BlueDIRECT four-cylinder petrol engines in the E-Class combine spontaneous response and exemplary power delivery with high efficiency and best-in-class emission performance. To achieve this goal, Mercedes-Benz transferred the BlueDIRECT technology from the V6 and V8 engines into the four-cylinder models. Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further by the engineers into third-generation direct petrol injection with spray-guided combustion. The system pressure is now up to 200 bar and is variably optimised according to the engine's characteristic map. Completely newly developed piezo injectors allow up to five injections per power stroke for the best possible mixture formation.

The third-generation direct injection system also features "rapid multi-spark ignition" (MSI). Following the first spark discharge and a brief combustion period, the coil is quickly recharged and a further spark is discharged. The MSI system enables up to four sparks to be discharged in succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition.

The rapid multi-spark ignition can be actuated to vary both the timing of the sparks and the combustion period to suit the relevant operating point. This provides scope for the best possible centre of combustion and improved residual gas compatibility. This in turn reduces fuel consumption. The result of this is excellent utilisation of the fuel with minimum emissions.

In conjunction with continuous adjustment of the intake and exhaust camshaft, the direct injection system also provides the essential basis for so-called scavenging. As a result of a partial overlap of the opening times of the intake and exhaust valve, part of the drawn-in cold fresh air conveys the hot exhaust gas contained in the cylinder into the exhaust manifold, thereby improving the filling level substantially in comparison with the conventional mode of operation. Due to the increased mass flow in the exhaust line, the turbocharger additionally responds considerably faster at low revs in particular, avoiding turbo lag.

A new thermal management system has also been developed: in a cold state, a switchable water pump with flow-optimised ball valve ensures that no coolant flows through the engine, providing for swift heating-up of the combustion chambers after starting up the engine. The thermostat is electronically controlled and the coolant temperatures are adjusted according to driving style and ambient conditions. The thermostat itself is also a flow-optimised ball valve. In the interest of high efficiency, the volumetric flow of the oil pump is also controlled as in the V engines.

All engine variants are designed for operation with E10 premium petrol and an octane number of 95 RON.

The petrol engines
In September 2013, the E 200 Natural Gas Drive with bivalent natural gas drive will complete the comprehensively updated range of drives for the E-Class. The 120 kW (163 hp) four-cylinder engine in this Saloon model can be run both on premium petrol and natural gas.

Powerful diesel engines in the best efficiency class

Some of the diesel models of the E-Class are available as BlueTEC models fitted with the established SCR (selective catalytic reduction) technology and as such meet the EU6 emissions standard.

The engine range is supplemented with the E 300 BlueTEC HYBRID. It combines the four-cylinder diesel engine (150 kW/204 hp) with an electric motor (20 kW/27 hp). The E 300 BlueTEC HYBRID consumes 4.1 l/100 km and produces CO2 emissions of 107 g/km. As such it occupies the leading position among the most economical models in the upper medium-size category.

The diesel engines
ECO start/stop function with direct-start

The ECO start/stop system included as standard in all models operates with the starter-supported ECO start/stop function. This means that when the engine is switched off, the attitude of the crankshaft is registered by a novel crankshaft sensor so that the engine control unit knows the positions of the individual cylinders. On restarting, it can then select the cylinder that is in the most suitable position for first ignition. After the starter has briefly turned over the engine, reliable injection, ignition and combustion are immediately possible in the ideally positioned cylinder.

Optimised drive train

Mercedes-Benz will also offer two transmissions for the E-Class in the future: a 6-speed manual transmission with high ease of shifting and short shift travel, and the 7G-TRONIC PLUS automatic transmission with DIRECT SELECT lever and DIRECT SELECT shift paddles. The features of the latest evolutionary stage of 7G-TRONIC PLUS include a new torque converter with reduced slip, an ECO shift programme with an improved ratio spread and an auxiliary oil pump to maintain the operating pressure during automatic stops. Low-friction components and low-viscosity fluid help to reduce the operating pressure.

A new feature is the short-term M mode. The benefit of this: if the driver has shifted up or down manually, after a set period of time the transmission independently switches back to automatic, fuel-efficient shift mode. This set period of time is lengthened in specific conditions (no accelerator pedal use, e.g. on downhill gradients, high lateral acceleration, e.g. when cornering, or if falling below a minimum speed when coming to a standstill), and return to automatic mode is prevented.

In short-term M mode as well as in "fixed" M Mode, the driver receives prospective gear change recommendations in the multifunction display of the instrument cluster, to enable an efficient driving style.

4MATIC all-wheel drive

Traction and driving stability can also be improved in the E-Class with the 4MATIC all-wheel drive system - particularly in difficult road conditions. As ever, the combination of the ESP® vehicle dynamics control system with the 4ETS electronic traction system makes regular differential locks superfluous. This saves weight and noticeably increases driving safety as well as ride comfort. The transfer case of the all-wheel drive is integrated into the main transmission.

The all-wheel drive models impress with:

- good traction characteristics, with a power distribution ratio on the front and rear axles of 45:55
- low fuel consumption due to the improved efficiency of the drive train
- additional weight of only 70 kg, compared with additional weight of up to 120 kg in the case of the competition
- unchanged bodyshell as well as unrestricted interior and luggage compartment space due to the compact design

The following engines are available with 4MATIC:

- E 250 CDI 4MATIC, 150 kW (204 hp), 500 Nm
- E 350 BlueTEC 4MATIC, 195 kW (265 hp), 620 Nm
- E 300 4MATIC, 185 kW (252 hp), 340 Nm
- E 400 4MATIC, 225 kW (306 hp), 370 Nm
- E 500 4MATIC, 300 kW (408 hp), 600 Nm

II. Chassis and suspension: The basis for superior handling

All of the models of the E-Class family will in future be fitted with an electromechanical Direct-Steer system as standard. This combines the speed-dependent power assistance of speed-sensitive steering with a variable ratio across the steering angle range. The power steering assistance provided by the rack and pinion steering gear is controlled on-demand and therefore contributes towards efficiency.

Advantages of the electromechanical Direct-Steer system:

- improved agility thanks to more direct steering response
- comfortable handling and high levels of steering comfort across all speed ranges
- considerable savings potential, since energy is only required when steering occurs
- enables the use of innovative assistance systems, such as Active Parking Assist

Four suspensions to choose from

For the E-Class, Mercedes-Benz is offering four refined suspension configurations:

- the standard model and ELEGANCE line are fitted with the DIRECT CONTROL suspension with selective damping system, configured for comfort
- the sportily configured DIRECT CONTROL suspension with selective damping system is positioned 15 mm lower and part of the AVANTGARDE line
- the DIRECT CONTROL lowered sports suspension is available in conjunction with the Exterior Sports package and AMG Sports package
- the AIRMATIC air suspension with electronically controlled damping system is fitted as standard on the V8 models. The Estate is fitted as a matter of course with rear-axle air suspension with integrated level control.

On the front axle, the established 3-link front suspension helps to ensure optimum driving dynamics. Both of the links (torque strut and cross strut) in the lower link plane determine the comfortable characteristics of the axle. The third link, the tie rod, forms part of the rack-and-pinion steering system.

At the rear is the familiar multi-link independent rear suspension, featuring a lightweight design. It provides good wheel control qualities for high levels of comfort and excellent driving dynamics.

All suspension variants feature impressive sensitivity and ride characteristics and help to ensure a high level of handling safety.

Excellent braking with ADAPTIVE BRAKE

The brake system in the E-Class is fitted with the ADAPTIVE BRAKE as standard. Depending on the engine variant, the following braking systems are used on the front axle with internally ventilated brake discs:

- 1-piston floating brake callipers with different sized brake discs for the 4-cylinder and V6 engine variants
- 4-piston floating brake callipers for the V8 engine variants

On the rear axle, the E-Class is braked by 1-piston floating brake callipers with different sized brake discs. In the case of the V6 and V8 engine variants, the brake discs are internally ventilated.

All of the engines have a foot-operated parking brake with integrated, automatic cable adjustment. The force applied by the driver is distributed to two additional drum brakes on the rear axle via the brake cable in the centre tunnel. Automatic adjustment helps to reduce the servicing costs.

Credits: Daimler AG

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