Mercedes-AMG has delivered the details on the new AMG SL43, which joins the line-up as the entry-level model for the AMG SL roadster. The new SL is available only as an AMG product, so there is no base Mercedes-Benz version of this car.
The SL 43 is expected in U.S. dealerships this summer, carrying a starting price of $111,050, including the $1,150 destination charge. As with all current Mercedes SL (Sports-Light) roadsters, the SL 43 is a soft-top convertible 2+2 design.
Mercedes has backtracked from the retractable hardtops to save weight. Currently the SL line starts with the twin-turbo V-8 SL 55 at $138,550, and includes the even more powerful SL63 at $179,250, so the new SL 43 is dramatically more affordable.
Turbo-Hybrid Tech
Under the hood of the SL 43 is an AMG-enhanced 2.0-liter turbocharged M139 engine featuring an electric exhaust gas turbocharger. This is the same engine found in the CLA, GLA, and C-Class AMG products. The electrically assisted turbo technology is a road-going version of the units used by the Mercedes-AMG Petronas F1 Team.
Here’s how it works: An electric motor around 1.6 inches in diameter is mounted directly on the turbocharger shaft between the turbine wheel on the exhaust side and the compressor wheel on the intake side. The motor drives the shaft of the turbocharger and accelerates the compressor wheel before the exhaust gas flow takes over, as in a conventional turbo.
The new turbocharger is designed to provide spontaneous throttle response across the entire rpm range without any lag time while the system spools up. The electric boost part of the turbocharger is operated by the 48-volt electrical system, which also feeds the belt-driven starter-generator mild hybrid system. With the new tech, the SL 43 has an output of 375 horsepower and a maximum torque of 354 pound-feet. The SL 43 accelerates from 0 to 60 mph in just 4.8 seconds on its way to an electronically limited 170 mph top speed.
“The electric exhaust gas turbocharger is a fascinating example of the extensive transfer between Formula 1 technology and the development of production vehicles,” said Jochen Hermann, chief technical officer of Mercedes‑AMG GmbH. “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.”
The second-generation starter-generator also functions as a mild hybrid in the 48-volt on-board electrical system. The hybrid aspect enables fuel-saving functions such as gliding and recuperation to maximize efficiency. The 48-volt technology also increases comfort, as the transitions between the start-stop function and gliding mode function are almost imperceptible, according to Mercedes-Benz.
Traditional Rear-Drive Layout and Aluminum Space Frame
The SL 43 will feature a longitudinal engine paired with the AMG Speedshift 9-speed multi-clutch transmission. This unit uses a wet start-off clutch in place of a traditional torque converter. This design reduces weight and, thanks to its lower inertia, optimizes the response to accelerator pedal input, especially during spurts and load changes.
The new SL model range is based on a completely new vehicle architecture developed by Mercedes‑AMG. Constructed from lightweight aluminum composite, the chassis consists of an aluminum space frame with a self-supporting structure.
Materials used include aluminum, magnesium, fiber composites and steel for the windshield frame. This serves as rollover protection in conjunction with the automatic roll-bar system behind the rear seats, which pops up when needed.
Why Go Ragtop?
Mercedes chose an electrically raised soft top instead of the previous retractable metal roof. The move saved 46 pounds, and it helped drop the center of gravity. The Z-fold design saves space and weight, making it possible to omit a conventional soft top compartment cover. The three-layer design consists of a tightly stretched outer shell, a roof liner, and an acoustic mat made of high-quality PES fleece inserted in between.
Opening and closing takes about 15 seconds and is possible up to a speed of 37 mph. The soft top is operated using the switch panel in the center console and the central multimedia touchscreen. There’s even a nifty little animation that shows how the process is progressing.
Serious Suspension and Brakes
The SL 43 features AMG suspension and can be fitted with the newly developed AMG Ride Control suspension with aluminum shock absorbers and lightweight coil springs. The new SL model series is the first production vehicle ever from Mercedes-AMG to feature a multi-link front axle with five links arranged entirely within the wheel rim. At the rear axle, a five-link design also controls the wheels.
To reduce unsprung weight, all suspension links, steering knuckles and wheel carriers on the front and rear axles are made of forged aluminum. The multi-link concept controls each wheel with the least amount of elastic movement.
“The high camber and track stability not only enables high cornering speeds, it also provides the driver with optimal road contact at the high cornering limit,” Mercedes says.
The latest generation of AMG adaptive adjustable damping is available as an option for the AMG SL43. The suspension control unit uses data analysis, including acceleration and wheel travel sensors, to adjust the damping force for each wheel in a few milliseconds to suit the situation.
The driver can pre-select the basic setup via the AMG Dynamic Select driving modes, choosing from full dynamics in “Sport+” mode to smooth cruising in the “Comfort” setting. In addition, the tuning can be adjusted in three stages independently of the driving modes via a dedicated button.
The AMG composite brake discs in the SL 43 are particularly light. The brake disc is made of cast steel while the center “hat” is made of aluminum. This design saves space, which is used for even better brake cooling. The directional perforation on the brake discs 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.
Just in Time for Summer
As mentioned, the SL 43 is expected at Mercedes-Benz dealerships this summer. With a starting price closer to $100,000 than its V-8-powered brethren, the SL 43 will open up the top tier of AMG ownership to a wider audience, and that’s always a good thing.