4-Pot SL43 AMG - Press Release

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Staff member
May 21, 2003
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Apr 6, 2022
Electric exhaust gas turbocharger derived directly from Formula 1™ for the first time in a production vehicle
Affalterbach. Following the two variants with V8 engines, Mercedes-AMG presents the SL 43 (combined fuel consumption 9.4-8.9 l/100 km, combined CO2 emissions 214-201 g/km),[1] a technically innovative entry-level model of the newly developed roadster icon. Under the bonnet of the open-top 2+2-seater with fabric soft top is an in-line four-cylinder petrol engine with two litres displacement that provides the befitting propulsion. This is the first time in the world that an electric exhaust gas turbocharger is being used in a production vehicle. This technology comes from Formula 1™. The system in the SL 43 is a direct derivative of the development successfully used by the Mercedes-AMG Petronas F1 Team for many years in the premier class of motorsport. The new form of turbocharging guarantees particularly spontaneous throttle response across the entire rev range, thereby offering an even more dynamic driving experience while increasing efficiency at the same time. The turbocharger is operated via the 48-volt electrical system, which also feeds the belt-driven starter-generator (RSG). As a result, the Mercedes-AMG SL 43 has an output of 280 kW (381 hp) and a maximum torque of 480 Nm, plus an additional short-term boost of 10 kW (14 hp) from the RSG in certain driving situations. The new entry-level model in the SL family also shines with extensive standard equipment. In addition, numerous options that enhance comfort and safety offer a wide range of possibilities for individualisation.

In the 70 years of its development history, the SL experienced the transformation from a thoroughbred racing car to an open-top luxury sports car - and has long enjoyed legend status, not least for this reason. The new Mercedes-AMG SL now marks another milestone in the model's history. It combines the distinct sportiness of the original SL with the unique luxury and technological excellence of the modern Mercedes-AMG models. As the new entry-level model in the series, the SL 43 is a particularly good example of this. It is the world's first series-produced vehicle to feature an electric exhaust gas turbocharger. This technology comes directly from Formula 1™ and solves the trade-off between a small, fast responding supercharger that nevertheless achieves comparatively low peak power and a large supercharger with high peak power that only responds delayed. With its innovative engine concept, the new entry-level model of the 2+2-seater roadster is aimed more at particularly tech-savvy buyers. With its combination of a comparatively light four-cylinder engine on the front axle and rear-wheel drive, the SL 43 also displays distinctly discrete handling characteristics.
"In its long history, the SL has repeatedly set technological milestones. For example, while the legendary 300 SL Gullwing in 1954 was the world's first series-produced passenger car with direct petrol injection, the new Mercedes-AMG SL 43 is now the very first series-produced vehicle with an electric exhaust gas turbocharger. With this technology, the SL also has an outstanding performance range in its entry-level version. This means that our seemingly smallest SL combines the typical AMG Driving Performance with luxury and comfort at the absolute top level. What's more, with this innovative engine we are undoubtedly also appealing to a wider clientèle", says Philipp Schiemer, Chairman of the Board of Management of Mercedes‑AMG GmbH.
"The electric exhaust gas turbocharger is a fascinating example of the extensive transfer between Formula 1 technology and the development of production vehicles. In implementing this in conjunction with our powerful M139 four-cylinder, we were also able to draw on the enormous wealth of experience of our colleagues at Mercedes-AMG High Performance Powertrains. The technology increases agility and thus driving fun, while at the same time improving the efficiency of the drive system. We are pursuing ambitious goals with a view to our electrified future. Innovative components such as the electric exhaust gas turbocharger help us to achieve this", says Jochen Hermann, Chief Technical Officer of Mercedes‑AMG GmbH.
Electric exhaust gas turbocharger improves engine responsiveness
The operating principle of the electric exhaust gas turbocharger is based on the same technology used by the Mercedes-AMG Petronas F1 Team. An electric motor around four centimetres thin is integrated directly on the turbocharger shaft between the turbine wheel on the exhaust side and the compressor wheel on the intake side. Electronically controlled, this drives the shaft of the turbocharger directly and thus accelerates the compressor wheel before the exhaust gas stream starts to drive it conventionally.
This significantly improves immediate response from idle speed and across the entire engine speed range. The combustion engine responds even more spontaneously to accelerator pedal input, while the overall driving experience is more dynamic. In addition, the electrification of the turbocharger enables higher torque at low revs. This also increases agility and optimises acceleration from a standstill. Even when the driver takes their foot off the accelerator or applies the brakes, the technology of the electric turbocharger is able to maintain the boost pressure at all times. This ensures so that a continuous immediate response.
The turbocharger, which is operated via the 48-volt on-board electrical system, works at speeds of up to 170,000 rpm, which enables a very high airflow rate. The turbocharger, electric motor and power electronics are connected to the combustion engine's cooling circuit to create an optimal temperature environment at all times. In combination with the internally named M139 two-litre, in-line four-cylinder engine, the innovative technology in the SL 43 produces a rated output of 280 kW (381 hp) at 6750 rpm. The maximum torque of 480 Nm is available between 3250 rpm and 5000 rpm. Depending on the situation, the system also guarantees an additional boost of 10 kW (14 hp) for a short time from the belt-driven starter generator (RSG).
The second-generation RSG also functions as a mild hybrid in the 48-volt on-board electrical system, which in addition to the temporary power boost enables functions such as gliding mode and energy recovery for maximum efficiency. At the same time, the 48-volt technology also increases comfort, as the transitions between the start-stop function and the gliding mode function are almost imperceptible.
AMG SPEEDSHIFT MCT 9G transmission with wet start-off clutch and rear-wheel drive
The four-cylinder engine known as the M139, which has long been used transversely in Mercedes‑AMG compact models without an electric exhaust turbocharger, is positioned longitudinally in the SL 43. In the entry-level model in the SL series, which always features rear-wheel drive, it is also combined with the AMG SPEEDSHIFT MCT 9G transmission (MCT = Multi-Clutch Transmission) for the first time. A wet start-off clutch replaces the torque converter. It reduces weight and, thanks to its lower inertia, optimises response to accelerator pedal input, especially during spurts and load changes. The elaborately calibrated software ensures extremely short shift times as well as fast multiple downshifts if required. In addition, the intermediate throttle function in the "Sport" and "Sport+" driving modes delivers a particularly emotionally appealing gearshift experience. There is also the RACE START function, which ensures optimal acceleration from a standstill.
The driving performance is up to par: from a standstill, the SL 43 accelerates to 100 km/h in just 4.9 seconds if required, and the top speed is 275 km/h. In addition to the performance it offers, the entry-level model of the series is also distinguished by comparatively low consumption and emission figures.
AMG high-performance composite brake system for short braking distances
The newly developed AMG high-performance composite brake system guarantees excellent deceleration values and precise control. It impresses with short braking distances, sensitive response and last but not least with high stability and durability - even under extreme stress. Comfort functions include Hill Start Assist as well as pre-filling and dry braking in wet conditions. When the ignition is switched off and the vehicle is stationary, the parking position "P" is also activated. When starting off, the electric parking brake is released automatically.
The composite brake discs are particularly light: Driving dynamics and turn-in behaviour benefit from the reduced unsprung masses. Brake disc (made of cast steel) and brake disc pot (made of aluminium) are now connected with special pins. This design saves space, which is used for even better brake cooling. The directional perforation is also new: In addition to the weight saving and better heat dissipation, this solution scores points with a faster response in wet conditions as well as better pad cleaning after braking.
Optional rear-axle steering combines agility and stability
The Mercedes-AMG SL 43 can be equipped with active rear-axle steering (HAL) as an option. Depending on the speed, the rear wheels steer either in the opposite direction (up to 100 km/h) or in the same direction (faster than 100 km/h) as the front wheels. The system thus enables both agile and stable driving characteristics. The front-wheel steering ratio is more direct, making it easier to steer the vehicle at the limit with less steering effort.
Six driving modes and AMG DYNAMICS: from comfortable to dynamic
The five AMG DYNAMIC SELECT driving modes "Slippery", "Comfort", "Sport", "Sport +" and "Individual", as well as the "RACE" mode included in the optional AMG DYNAMIC PLUS Package, enable a wide spread of vehicle characteristics from comfortable to dynamic. The distinct driving modes offer an individual driving experience, precisely tailored to different driving conditions. As a feature of the AMG DYNAMIC SELECT driving modes, the SL models also feature AMG DYNAMICS. This integrated vehicle dynamics control expands the stabilising functions of ESP® with interventions that enhance agility in the steering characteristic and in ESP® additional functions. When cornering at speed, for example, brief braking intervention at the inner rear wheel generates a defined yawing moment around the vertical axis for responsive and precise turn-in.
SL equipment programme: great variety for an individual look
With the details of its extensive standard equipment as well as many additional options available, the Mercedes-AMG SL 43 offers a broad individualisation spectrum for a wide range of customer wishes - from sporty and dynamic to luxuriously elegant. This includes twelve paint finishes including the two exclusive SL colours hyper blue metallic and MANUFAKTUR monza grey magno, three roof colour variants and several new wheel designs.
Three exterior design packages are available to sharpen the look further and make it more elegant or more dynamic.
  • The AMG Exterior Chrome Package contains elegant high-gloss chrome accents on the front apron, the side sill trim and the rear.
  • In the AMG Night Package, selected exterior elements are finished in high-gloss black, such as the front splitter, the side sill trims, the mirror caps and the trim element in the rear diffuser. Added to this are darkened tailpipe trims. Depending on the chosen paint finish, this results in striking contrasts or flowing transitions.
  • The AMG Night Package II includes additional elements in high-gloss black, including radiator grille, typography and Mercedes star at the rear.
  • With the AMG Exterior Carbon Package, lightweight components made of carbon fibre evoke the SL's motorsport history. The carbon parts include the front splitter and the flics in the front bumper as well as the trim strip in the side member trim. Furthermore, there are tailpipe trims in high-gloss black and the trim strip in the diffuser in carbon or high-gloss black.
AMG DYNAMIC PLUS Package for maximum driving pleasure
The AMG DYNAMIC PLUS Package, which combines numerous high-performance components, is optionally available for the SL 43:
  • Dynamic AMG engine mounts connect the engine more rigidly or more flexibly to the body, depending on the driving situation. In every driving situation, this results in the best possible balance between driving dynamics and comfort.
  • The electronically controlled AMG limited-slip rear differential distributes the required power to the wheels even more promptly and precisely during dynamic cornering and rapid acceleration, thus guaranteeing maximum traction.
  • The "RACE" driving mode delivers race track performance at the touch of a button with even more spontaneous engine response and a more direct accelerator pedal characteristic. Selectable as an additional driving mode via the AMG steering wheel buttons.
  • The lowering by ten millimetres lowers the vehicle's centre of gravity and additionally stabilises the vehicle.
  • The yellow-painted AMG brake callipers visually underline the increased driving dynamics potential.
Driving assistance systems and MBUX: intelligent helpers in the background
With the aid of numerous sensors, cameras and radar, the driving assistance systems, some of which are optional, monitor the traffic and surroundings of the new SL 43. If necessary, the intelligent helpers can intervene at lightning speed. As in the current generations of the Mercedes C-Class and S-Class, the driver is supported by several new and enhanced systems. This is done in everyday situations, for example, by helping with speed adaptation, distance control, steering and lane changes. This makes it easier to react to impending collisions. The functioning of the systems is visualised by a new display concept in the instrument cluster.
The new assistance display in the instrument cluster shows comprehensibly and transparently how the driving assistance systems work in a full-screen view. The driver can see their car, lanes, lane markings and other road users such as cars, trucks and two-wheelers in an abstracted 3D way there. The system status and operation of the assistants are visualised in this depiction of the surroundings. The new, animated assistance display is based on a 3D scene generated in real time. This dynamic, high-quality representation makes the operation of the driving assistance systems transparent as an augmented reality driving experience.
Numerous connectivity services available
The MBUX (Mercedes-Benz User Experience) infotainment system enables extensive operating options and many digital services from Mercedes me connect. The strengths include the intuitive operating concept via touch screen or touch control buttons on the steering wheel, Smartphone Integration of Apple CarPlay and Android Auto as well as hands-free operation via Bluetooth connection and Digital Radio (DAB and DAB+). In conjunction with MBUX, customers already have access to connectivity services such as Live Traffic Information. Mercedes me connect makes the new SL altogether more intelligent: Additional functions can be used before and after the journey or while on the road. All that is required is to link the roadster to a Mercedes me account in the Mercedes me Portal and accept the Terms of Use. Thanks to navigation with Live Traffic Information and Car-to-X communication, the customer drives with real-time traffic data. This way, traffic jams can be avoided efficiently and valuable time can be saved. Networked vehicles exchange information about traffic events by means of car-to-x communication.
Technical data[1]
Mercedes-AMG SL 43

Number of cylinders/arrangement 4/in-line
Rated outputkW/hp280/381
at engine speedrpm6750
Additional output (Boost)kW/hp10/14
Rated torqueNm480
at engine speedrpm3250-5000
Compression ratio 10.0
Mixture formation combined direct petrol injection and intake manifold injection, turbocharging by means of electrically assisted exhaust gas turbocharger
Power transmission
Drive system layout Rear-wheel drive
Transmission AMG SPEEDSHIFT MCT 9G (automatic transmission with wet multi-disc start-off clutch)
Gear ratios
1st/2nd/3rd/4th/5th/6th/7th/8th/9th gear 5.35/3.24/2.25/1.64/1.21/1.00/0.87/0.72/0.60
Reverse 4.80
Front axleAMG RIDE CONTROL suspension with aluminium double wishbones, anti-squat and anti-dive geometry, lightweight coil springs and stabiliser bar
Rear axleAMG RIDE CONTROL suspension with aluminium double wishbones, anti-squat and anti-dive geometry, lightweight coil springs and stabiliser bar
Brake systemHydraulic dual-circuit brake system; 390 mm composite brake discs at front, vented and perforated, 6-piston aluminium fixed calliper; 360 mm composite brake discs at rear, vented and perforated, 1-piston aluminium floating calliper; electric parking brake, ABS, Brake Assist, 3-stage ESP®
SteeringElectromechanical speed-sensitive power steering with rack and pinion, variable steering ratio (12.8:1 at dead centre) and variable power assistance
Wheelsfront: 9.5 J x 19; rear: 11 J x 19
Tyresfront: 255/45 ZR 19; rear: 285/40 ZR 19
Dimensions and weights
Front/rear trackmm1665/1629
Turning circlem12.84
Boot capacityl213-240
Kerb weight acc. to ECkg1810
Tank capacity/of which reservel70/10
Performance, consumption, emissions
Acceleration 0-100 km/hsec.4.9
Top speedkm/h275 (electronically limited)
Combined fuel consumption, WLTPl/100 km9.4-8.9
Combined CO2 emissions, WLTPg/km214-201
[1] The stated figures are the measured "WLTP CO₂ figures" in accordance with Article 2 No 3 Implementing Regulation (EU) 2017/1153. The fuel consumption figures were calculated on the basis of these figures.
Many current SL owners dont like them. I love it. Been showing my wife the pictures.....so far, she loves the colour......(which beside space for her hand bag, coat and comfort is all she cares about).
1810kg .. heavy for a 4 cylinder fabric roof

my R231 SL with 6 cylinder and metal roof is 1730kg
Like that a lot, but would be nicer with a metal roof. No worries about the local neds
A 2 litre engine pushing out 381 bhp ... what could possibly go wrong?
A 2 litre engine pushing out 381 bhp ... what could possibly go wrong?
If it was designed to do it, nothing other than the usual ICE random faults. The issue comes when a 2L engine is designed to produce 120bhp and then pushed to produce three times that.
^ They have proved themselves a strong unit, even when MSL are remapping them to produce 400+BHP.

It's not unusual when you consider Cosworth for example were remapping their 2lt engines well in excess of 400BHP back in the 80's with reliability.
If it was designed to do it, nothing other than the usual ICE random faults.

Virtually no issues with the A35/A45s have there?

AFAIK the M139 has only existed for 3 years, so I guess we will see. IMHO the SL is a bit different to the A Class in terms of life expectancy, and I personally doubt we'll see these engines running happily in 30+ years time as the large capacity ones in previous generations typically do.

Ford are currently busy replacing small Ecoboost engines under warranty / goodwill ... bad luck to anyone who has one let go when they're a bit older though.
The first A45 was unveiled way back in 2013. I don't think I've read a single failure post on any of the forum by frequent.
Let's be honest, these engines are better in every way apart from the sound (maybe smoothness also) I'm afraid we need to embrace smaller engines as the future before EVs :(
The first A45 was unveiled way back in 2013. I don't think I've read a single failure post on any of the forum by frequent.

The M139 engine used in this SL didn't appear in the A45 until 2020 (W177). Before that (W176) it had the less powerful M133.
Beautiful looking car, I really like this new generation SL (maybe not so much the price 😂).

It takes some adjustment to accept a 4-pot SL though, although I accept there's an argument to say it harks back to the W121. I get why it exists, and appreciate nothing is the same anymore, I think it's just a bit of a mental block due to 4 cylinder engines never really being associated with a premium flagship model range before now. As good as modern engines are too, I'm sure the creamy smoothness associated with 6 and 8 cylinder engines won't quite be replicated entirely.

The modern world eh? Not sure I'm fully ready 😂. As I said though, despite a bit of criticism elsewhere, I think they look really good.
In addition to this and the V8 bi-turbo models there will be an 800+ PS ePerformance hybrid model too, so there will be quite a range and something for almost everyone (except normally aspirated manual transmission fans).
I only have 333hp but have very rarely thought I needed more power
I thought you were comparing power to weight ratios however I agree with you. I have ~362 hp and have never wished for more power.
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Ford are currently busy replacing small Ecoboost engines under warranty / goodwill ... bad luck to anyone who has one let go when they're a bit older though.
What problem or problems are there with the Ecoboost engines?

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