Press Kit: The new Mercedes-Benz R-Class
Oct 24, 2005
Powertrain: Dynamism as standard
  • Choice of two newly developed six-cylinder engines and a V8 engine
  • All engines with 7G-TRONIC seven-speed automatic as standard
  • Permanent all-wheel drive in combination with the 4ETS traction system
The outputs of the engines available for the R-Class range from 165 kW/224 hp to 225 kW/306 hp. They include two smooth-running petrol units with six and eight cylinders and the new V6 diesel engine by Mercedes-Benz - a powerful trio which provides optimal conditions for dynamic driving pleasure and a high level of long-distance comfort.
This is borne out by the performance figures for the Grand Sports Tourer:
  • Acceleration: The top-of-the-line V8 model R 500 requires just 6.9 or 7.0 seconds to sprint from standstill to 100 km/h, thereby putting many a sporty saloon firmly in the shade. The R 350 accelerates to 100 km/h in 8.3 or 8.4 seconds and the R 320 CDI requires 8.7 or 8.8 seconds.
  • Maximum speed: The maximum speed of the R-Class is 245 km/h (R 500). The R 350 and R 320 CDI have a top speed of 230 and 222 km/h respectively.
  • Flexibility: The exemplary torque characteristics of the engines and their perfect interaction with the 7G-TRONIC seven-speed automatic transmission make themselves felt during an intermediate sprint from 60 to 120 km/h. The figures: 6.6 or 6.7 seconds for the R 500, 8.1 or 8.2 seconds for the R 350 and 8.7 or 8.8 seconds for the R 320 CDI.
  • Fuel consumption: In this area too, the engines in the R-Class show that they are among the most modern high-tech units. In the EU driving cycle the six-cylinder diesel in the R 320 CDI consumes 9.3 litres of fuel per 100 kilometres, while the V6 petrol-engined R 350 requires 11.4 or 11.5 litres to cover 100 kilometres and the eight-cylinder of the R 500 requires 13.3 litres of premium unleaded (all figures: combined consumption).
  • R 320 CDI: V6 diesel with outstanding output and torque
    With 165 kW/224 hp the V6 engine in the R 320 CDI is among the most powerful six-cylinder diesel units in this displacement class. This newly developed engine also generates outstanding torque: 510 newton metres are already available from 1600 rpm.
    The six-cylinder unit is equipped with third-generation common-rail direct injection. This means that the injectors, high-pressure pump and electronic engine management operate even more efficiently, further reducing fuel consumption, exhaust emissions and combustion noise. Instead of the previous solenoid valves, the injectors are equipped with piezo-ceramics whose crystalline structure changes within microseconds under an electric voltage. The engine developers used this effect, which was discovered in 1880 by the brothers Pierre and Jacques Curie, to lift the needle jet at the tip of the injector with a precision of mere thousandths of a millimetre and thereby achieve an extremely fine jet of fuel.
    Moreover, piezo injectors are considerably lighter and operate at twice the speed of conventional solenoid valves. With a response time of only 0.1 milliseconds, the fuel injection process can be even more precisely suited to the current load and engine speed situation, with favourable effects on emissions, fuel consumption and combustion noise. The number of fuel injections per power stroke is increased from three to five thanks to this piezo technology.
    Mercedes engineers have also made improvements to other components of the common-rail system and the injection process:
    • The hydraulically optimised injector nozzles have eight holes (previously seven), which ensures even finer distribution of the fuel within the combustion chamber and more efficient mixture formation.
  • The inlet-metered high-pressure pump operates with a maximum injection pressure of 1600 bar.
  • The pilot injection process developed by Mercedes-Benz, which ensures a smoother combustion process and thereby audibly reduces the operating noise of the engine, takes place twice in succession in the new V6 engine. Small pilot quantities of fuel are injected within less than a millisecond and preheat the combustion chambers even more efficiently.
  • To burn off the soot particles in the particulate filter, there is a double post-injection of fuel when required.
  • The new V6 diesel engine is aspirated by a VNT (Variable Nozzle Turbine) turbocharger. This technology enables high levels of output and torque to be achieved even at low engine speeds. The electrically controlled VNT turbochargers are able to vary the angle of their turbine blades rapidly and precisely to suit the operating status of the engine, and can therefore use the largest possible volume of exhaust gas to compress the intake air and build up charge pressure. More efficient cylinder charging and therefore higher torque are the results of variable, demand-related turbocharger control. Moreover, electric VNT technology allows a precise interaction with other units which are responsible for reducing untreated emissions and for exhaust gas aftertreatment.
    The turbocharger is combined with a downstream intercooler which reduces the temperature of the compressed, heated air by up to 95 degrees Celsius, allowing a larger volume of air to reach the combustion chambers. Behind the intercooler there is an electrically controlled flap which enables the V6 engine to be throttled back precisely when the exhaust gas recirculation is in operation. This electrically regulated control flap allows the volume and mix of the exhaust gases added to the combustion air to be very precisely metered. To optimise the volume of recirculated exhaust gas, it is abruptly cooled in a high-performance heat exchanger. Acting in conjunction with the hot-film air mass sensors integrated into the intake air ducts, which provide the engine control unit with precise information about the current volume of intake air, this significantly reduces nitrogen oxide emissions. The combustion air then flows into the charge air distribution module, which supplies each cylinder in equal measure. The distribution module features an integral, electrically controlled intake port shut-off function with which the intake port cross-section for each cylinder can be variably reduced. This modifies the swirl of the combustion air, ensuring that the charge flow to the cylinders is adjusted for the best possible combustion and exhaust emissions under any load and engine speed conditions.
    Emission control with two catalytic converters and a particulate filter
    Two oxidising catalytic converters clean the exhaust gases emitted by the new Mercedes diesel engine. One acts as a primary catalytic converter, and is ready for action very soon after a cold start thanks to its position close to the engine. This unit is accompanied by a downstream main catalytic converter. The purpose of the oxidation-type catalytic converters is to convert carbon monoxide and unburned hydrocarbons by combining them with oxygen to form chemical compounds (oxidisation). This efficient exhaust gas aftertreatment combined with the complex in-engine measures already enables the V6 diesel engine to meet the stringent EU4 exhaust limits. To lower exhaust emissions even further, Mercedes-Benz combines the new six-cylinder powerplant with a maintenance-free particulate filter.
    Mercedes-Benz has developed the first V6 diesel engine made of aluminium
    As a world first, Mercedes-Benz has developed a six-cylinder diesel engine with an aluminium crankcase and cast-in grey iron cylinder liners. It tips the scales at just 41 kilograms. Aluminium is also used for the cylinder heads, cylinder head covers, pistons, coolant pump, sump and charge pressure distributor. Plastics are also used to save weight. Components in the fresh and charge air ducting systems, damper filter and engine shrouding are of plastic.
    A likewise newly developed valvegear reduces both friction and moving masses: the 24 intake and exhaust valves are controlled by an overhead camshaft for each cylinder bank, via roller-type cam followers with hydraulic valve clearance compensation. The camshafts are driven by a tried-and-tested double-bush timing chain system into which the balancer shaft and the high-pressure pump for the fuel injection system are integrated.
    R 350: the new six-cylinder engine has an output of 200 kW/272 hp
    Output, torque, fuel consumption, comfort and exhaust emissions - these were also task areas of equal importance when developing the new V6 petrol engine. This up-to-date six-cylinder unit makes its mark in each of these disciplines. The interaction of the 24 valves can be controlled as required - depending on the engine load - by continuous, variable camshaft adjustment. This ensures an extremely rapid gas exchange in the cylinders. The angles of both the intake and exhaust camshafts can be continuously varied by 40 degrees, ensuring that the valves open or close at the best possible moment in any driving situation.
    This valve overlap when venting the exhaust gases and taking in the fresh mix-ture makes an efficient internal exhaust gas recirculation possible. This reduces the energy losses during the charge cycle in the cylinders, leading to a signifi-cantly lower fuel consumption. Under higher engine loads the camshaft adjustment feature is also used to optimise the valve overlap in line with the engine speed so that the combustion chambers are efficiently supplied with fresh mix-ture – which makes for a high power and torque output.
    An intake module produced in well-proven magnesium technology enables the air intake to be varied according to the engine load and rev speed. The length of the intake pipes leading to the cylinders is varied by means of flaps: at high engine speeds – from approx. 3500 rpm – the flaps are open and the air takes the shortest distance to reach the combustion chambers, producing a high engine output. At low engine speeds the flaps are closed, increasing the length of the intake duct. This creates pressure waves which assist the intake process and fundamentally improve the torque generated in the lower engine speed range. No less than 305 Newton metres are already available from 1500 rpm, which corresponds to about 87 percent of the maximum torque.
    Tumble flaps in the intake ducts improve combustion
    Electro-pneumatically driven flaps at the end of each intake duct are the special feature of the intake module in the Mercedes six-cylinder engine. These make a significant contribution to fuel economy. Mercedes engineers refer to these as tumble flaps, which in some measure indicates their purpose: they literally cause the fuel/air mix to tumble, increasing the turbulence of the airflow and causing it to enter the combustion chambers at higher speed, with a more uniform distribution. The result is better, more complete combustion.
    At part-throttle, the tumble flaps pivot upwards, optimising the airflow and in-creasing the speed of combustion – a benefit that makes itself particularly notice-able where the mixture is lean as a result of exhaust gas recirculation and which further reduces fuel consumption. Under higher engine loads the tumble flaps are not required, and can be completely recessed into the intake manifold so as not to impede the intake process. By virtue of the tumble flaps in the intake ducts, the engine's fuel consumption can be reduced by up to 0.2 litres per 100 kilometres depending on engine speed - while improving smoothness at the same time.
    Emission control using in-engine measures and catalytic converters
    The emission control system follows a two-stage concept: it is based both on so-phisticated engine-specific measures for a reduction in untreated emissions and on highly effective emission control using two catalytic converters located close to the engine. Each of these is equipped with two oxygen sensors - a control sensor and a diagnostic sensor - with linear control. This means that the oxygen sensors are already active immediately after a cold start, supplying information about the exhaust gas constituents for the electronic engine management system to process when controlling the warm-up phase. The engine-specific measures include for example variable camshaft adjustment, which makes efficient internal exhaust gas recirculation possible under partial load. A secondary air injection system is also used.
    R 500: V8 engine offers outstanding comfort and excellent performance characteristics
    The V8 engine in the new R 500 generates 225 kW/306 hp from a displacement of 4966 cubic centimetres. An electronically controlled intake module increases the torque available at low engine speeds and ensures that on both town and country roads, the engine is always able to respond immediately to the driver’s power requirements. More than 400 Newton metres are already available from 2000 rpm, corresponding to almost 90 percent of the maximum torque of 460 newton metres which the eight-cylinder unit places on tap at 2700 rpm and maintains up to 4750 rpm.
    Key engine and performance figures for the R-Class at a glance:
    R 320 CDI
    short/long wheelbase

    R 350
    short/long wheelbase

    R 500
    short/long wheelbase


    165 kW/224 hp

    200 kW/272 hp

    225 kW/306 hp

    Max. torque at rpm

    510 Nm
    1600-2800 rpm

    350 Nm
    2400-5000 rpm

    460 Nm
    2700-4750 rpm

    0–100 km/h

    8.7/8.8 s

    8.3/8.4 s

    6.9/7.0 s

    Max. speed

    222 km/h

    230 km/h

    245 km/h

    Fuel consumption

    9.3-9.5  l/100 km

    11.5-11.7 l/100 km

    13.3-13.9 l/100 km

    DIRECT SELECT perfects the operation of the seven-speed automatic transmission
    On board the new R-Class, the powerful six and eight-cylinder engines and the 7G-TRONIC seven-speed automatic transmission form a strong team. With a number of special technical features, this transmission fully exploits the characteristics of the engines and therefore makes a major contribution to brisk acceleration, rapid intermediate sprints, a favourable fuel consumption and a high level of gearshift comfort.
    The 7G-TRONIC transmission has a further special feature: DIRECT SELECT. This means that the conventional automatic selector lever in the centre console is replaced by a lever on the steering column, which the driver nudges to select the transmission settings "P", "N", "R" and "D". Operating commands are transmitted electronically by wire, which is why the system is referred to as "shift-by-wire". For drivers with sporty inclinations who wish to operate the transmission manually in certain driving situations, the new R-Class can be equipped with steering-wheel gearshift buttons as standard.
    Permanent all-wheel drive and 4ETS as standard
    The transfer case for the permanent all-wheel drive system is directly flanged to the 7G-TRONIC transmission. Torque distribution between the axles is 50:50. Propeller shafts transfer power to the front and rear axles, while a bevel differential compensates the speed of rotation between the axles.
    Traction control is provided by the well-proven 4ETS Electronic Traction System, which now has additional functions and is even more capable than before. 4ETS controls the distribution of torque to the wheels by triggering brief braking pulses based on the signals received from the ABS wheel sensors: if these sensors report that one or more wheels have lost their traction, they are automatically braked. At the same time the distribution of drive torque is changed: the torque fed to the wheels with good traction is increased in line with the braking effect on the spinning wheels, allowing progress to continue on loose or slippery surfaces.
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