New Generation Mercedes SL-Class In Depth

Press Release

Page 1: Overview
Page 2: Design
Page 3: Body & Interior
Page 4: Engines & Transmissions
Page 5: Chassis
Page 6: Tradition
Page 7: Specifications

Engines and transmissions: More power, more enjoyment

• SL 350: new V6 engine with output of 200 kW/272 hp

• SL 500: powerful V8 with 285 kW/388 hp

• SL 600: V12 biturbo engine with extra power and torque

• Available as an option: 7G-TRONIC Sport with shift paddles for SL 350 and SL 500

The engine is the heart and soul of a sports car. In no other vehicle segment is the subjective quality of the driving experience dominated to such an extent by the powerplant. With this in mind, the Mercedes engineers have provided the new-generation SL-Class with three newly developed engines, each of which offers more output and torque than the corresponding predecessor model.

The SL-Class engine line-up comprises three powerplants with six, eight and twelve cylinders. The basic unit, the new V6 engine with 200 kW/272 hp and 350 newton metres of torque, is also offered in many other Mercedes-Benz passenger-car model series. Higher output with lower fuel consumption is the message from this advanced six-cylinder engine with a displacement of 3.5 litres, 24 valves and four continuously adjustable camshafts. Compared with the V6 used previously in the SL-Class, the new unit offers an extra 20kW/27 hp of output (an increase of about 11 percent) and consumes 10.3 litres of fuel per 100 km in the NEDC cycle ??????????????????????????????????????? a good litre less than its predecessor.

The eight-cylinder engine in the SL 500 is a newly developed unit which has been providing the new S-Class with superbly assured performance since autumn 2005. With a displacement of 5.5 litres, the engine develops 285 kW/388 hp which represents an increase in performance of more than 26 percent compared with the previous V8. At 530 newton metres, its torque is also significantly higher ??????????????????????????????????????? about 15 percent ??????????????????????????????????????? than the maximum achieved by the previous engine. This high level of torque is available from 2800 rpm and remains constant throughout a wide engine speed range up to 4800 rpm, providing the ideal basis for powerful acceleration and fast intermediate sprints:

• The new generation SL 500 accelerates from zero to 100 km/h in 5.4 seconds and is therefore almost one second faster than the previous eight-cylinder Roadster.

• In third gear, the SL 500 accelerates from 60 to 120 km/h in just 5.0 seconds.

The newly developed eight-cylinder unit is the top powerplant in the new generation of Mercedes-Benz V-engines which was successfully introduced in mid-2004. Equipped with four valves per cylinder, continuously adjustable intake and exhaust camshafts, a two-stage intake module and tumble flaps in the intake ducts, the new V8 is one of the most powerful engines in its displacement class. Other technical highlights of the new eight-cylinder unit include special shifting camshafts. These reduce the pressure fluctuations in the exhaust tract which are inherent in the design and thus improve the engine's gas cycle significantly. The consequences of this measure include smoother running and higher torque in lower and medium engine speed ranges. The new Mercedes eight-cylinder powerplant employs the latest lightweight construction principles, with an aluminium crankcase, low-friction cylinder liners of aluminium/silicon alloy, a forged steel crankshaft and weight-optimised connecting rods.

The fact that, at 12.2 litres per 100 kilometres, the combined NEDC fuel consumption of the SL 500 remains at the level of the previous model despite having higher output and greater torque is a clear endorsement of the advanced design and high-tech features of the new Mercedes eight-cylinder unit. With a specific fuel consumption of 233 grams per Kilowatt hour (g/kWh) when operating at peak efficiency, and 345 g/kWh at part-throttle (2000 rpm, 2 bar), the engine has easily the lowest fuel consumption in this displacement and output class.

V12 engine: advanced powerplant with sophisticated biturbo system

The twelve-cylinder engine of the SL 600 reflects the wealth of experience and expertise which Mercedes-Benz brings to the development of high-tech powerplants. The Stuttgart-based automaker is the world's largest manufacturer of V12 engines for passenger cars. This top-of-the-range engine has been revised for the new generation SL-Class: thanks to a new, far more efficient electronic engine management system, output has been raised by 12 kW/17 hp to 380 kW/517 hp. Maximum torque is also up by 30 newton metres to a new high of 830 Nm ??????????????????????????????????????? and remains constant at this impressive level between 1900 and 3500 rpm.

With figures like these, it is clear that the SL 600 has ample resources to cope with every driving situation. It accelerates from 0 to 100 km/h in only 4.5 seconds and polishes off the 60 to 120 km/h sprint in 4.2 seconds. The maximum speed is electronically limited to 250 km/h. Combined NEDC fuel consumption is 14.3 litres per 100 kilometres. The V12 combines its impressive performance with exemplary smoothness and extremely quiet operation - ideal conditions for a refined, highly enjoyable driving experience.

Lightweight design: engine features aluminium and magnesium components

The crankcase of the twelve-cylinder engine is made from diecast aluminium while diecast magnesium is used for the cylinder-head covers. Fracture-split or "cracked" conrods made from high-strength forged-steel alloy, pistons made from a high-quality aluminium alloy, hollow camshafts of induction-hardened forged steel, a weight-optimised forged-steel crankshaft and a diecast aluminium sump feature among the other lightweight components of the engine which weighs just 263 kilograms and has a power-to-weight ratio of 0.71 kg/kW.

This exemplary lightweight design is complemented by the engine's equally impressive credentials with regard to its noise emissions and vibration characteristics. These qualities are inherent in the design of the new V12 unit: the V-angle of 60 degrees balances inertia forces and moments at source.

The space-saving positioning of the twin turbocharger turbines in the exhaust manifold maximises their efficiency. The compressed air flows through two engine-mounted water-cooled intercoolers located on the cylinder head covers. Depending on the engine load the air is cooled here by up to 100 degrees Celsius, so that its temperature and density are optimised for the combustion process. The water-intercoolers are integrated in a special low-temperature circuit. A demand-controlled, electric circulation pump transfers the heat between the water-intercoolers and the low-temperature cooler located in front of the engine which passes the heat from the water to the cooling air.

Overview of key engine data for the new SL-Class:

*Electronically governed

Sound design: newly developed exhaust systems for all three V-engines

The engine note has always been one of the defining characteristics of the sports-car driving experience. In order to add particular emphasis to the sporty character of the SL-Class, the Mercedes engineers have developed new exhaust systems for all three V-engines within the context of the model update measures. Their aim was to ensure that the updated models would have an emotionally engaging, dynamic engine note under load ??????????????????????????????????????? when accelerating, for example ??????????????????????????????????????? yet would still offer a high standard of long-distance comfort (one of the hallmarks of the SL) when cruising. Furthermore, all unwanted background noise was to be eradicated and emphasis given to those frequencies which are perceived as pleasant by the occupants.

Whether you are driving the SL 350, SL 500 or the SL 600 ??????????????????????????????????????? it takes only a few kilometres to conclude that the measures which have been taken are a resounding success. At low revs, in particular, the SL engines are pleasantly sonorous and distinctive without ever becoming intrusive. The new sound design makes it possible to appreciate the exceptional potential of any member of the SL engine line-up, whatever the driving situation.

Exhaust emissions: all engines comply with the most stringent standards

The design measures taken to achieve this comprise new anechoic rear silencers with precision-tuned pipe perforations, centre silencers which function as Helmholtz resonators (SL 350 only) and a newly developed switchover valve between the left and right exhaust pipes. Increased pipe diameters in the SL 350 and SL 500 as well as the optimised flow characteristics of the silencers result in lower exhaust counterpressure and thus contribute to the increased output. All the exhaust systems are made from particularly durable stainless steel and have full twin-pipe architecture. The new catalytic converters, which are fitted on the firewall near the engine and feature a tri-metallic coating, make it possible to do away with the additional underfloor catalytic converters which were used previously. The new units reduce the exhaust counterpressure, reach their operating temperature more quickly, offer more efficient aftertreatment of the exhaust emissions and have greater resistance to aging. The emission control system used by Mercedes-Benz also features internal exhaust-gas recirculation with secondary air injection. All three model variants of the SL-Class fall well within the most stringent emissions limits which currently apply and have the potential to satisfy the standards planned for the future, too.

Transmission: 7G-TRONIC for smooth, responsive gear changes

The V6 and V8 models of the new generation SL-Class are equipped as standard with the 7G-TRONIC seven-speed automatic transmission, the only passenger car transmission of this type in the world. 7G-TRONIC incorporates numerous engineering innovations which, in conjunction with the state-of-the-art engines, provide enhanced acceleration and mid-range power, lower fuel consumption and greater shifting comfort. The S/C selector in the centre console allows the driver to choose between "Sport" and "Comfort" driving programs which modify the characteristics of not only the transmission but also the accelerator pedal.

Optionally available: 7G-TRONIC Sport for even faster shifting

An entirely new feature is the 7G-TRONIC Sport transmission which is available as an option for the SL 350 and SL 500; as well as offering a manual shift program, it features shift paddles mounted on the steering wheel. The "M" manual program is activated by pressing the S/C/M button on the centre console; in this mode, the seven gears can be shifted using the two motorsport-style shift paddles on the multifunction steering wheel ??????????????????????????????????????? pulling briefly on the left paddle shifts down while the right paddle shifts up. In "M" mode, the system's electronics reliably maintain the last gear selected, even at full throttle. It is thus possible to make optimum use of the high pulling power of the V6 and V8 engines. However, depressing the accelerator fully triggers the kickdown function which causes the transmission to shift down in order to deliver maximum acceleration. Furthermore, 7G-TRONIC Sport reduces shift times by up to 30 percent in manual mode.

Transmission ratio: optimised thanks to wider overall spread

The special characteristics of the seven-speed automatic transmission are attributable to various different design features, the most important of which is the increase in the number of forward speeds from five to seven. This results in a wider overall ratio spread, while at the same time the ratios are also closer together than in the five-speed transmission. An optimal ratio can therefore be selected for virtually all driving situations. The fact that the electronic control unit has a greater number of ratios to choose from also reduces fuel consumption and increases smoothness. Depending on the driving situation, average engine speeds at 100 km/h are approximately twelve percent lower than with a five-speed automatic transmission. The optimal matching of engine speed to driving conditions means that the engine offers better fuel economy and also runs more quietly.

The Mercedes engineers have also made important advances in terms of the transmission's control logic: if the 7G-TRONIC transmission needs to shift down quickly through several gears ??????????????????????????????????????? under kickdown, for example ??????????????????????????????????????? a multiple downshift function comes into operation. Instead of changing gear sequentially, one gear at a time, the transmission shifts down by up to four gears at a time, depending on the driving situation, resulting in significantly faster shift times.

Extra comfort: torque converter lockup and torsional damper

The new seven-speed automatic transmission is fitted with a hydrodynamic torque converter with lockup clutch. Whenever possible, the lockup clutch creates a virtually rigid connection between the engine and the transmission shaft, thus preventing slip between the impeller and turbine, and thus power losses, in a wide range of operating situations. In the Mercedes-Benz seven-speed automatic transmission, the lockup clutch engages even in first gear, rather than only in the higher gears as on conventional automatic transmissions. For reasons of comfort, the torque converter lock-up clutch is slip-controlled and therefore engages very smoothly. Furthermore, the SL-Class has a new turbine torsion damper; this reduces vibrations, especially at low revs, and thus enhances comfort when operating in the partial load range.

Five-speed automatic transmission: also available with optional steering-wheel shift paddles

Power transmission in the SL 600 is handled by the proven five-speed automatic transmission. Thanks to the new, more efficient engine management system, it has been possible to develop a greater degree of differentiation between the "Sport", "Comfort" and "Manual" driving programs ??????????????????????????????????????? which translates into a more compelling or more comfortable driving experience, depending on the driver's choice. Steering-wheel gearshift paddles which allow motorsport-style gear changing are available as an optional extra.