New 2021 Mercedes-Benz SL: bespoke shell shown ahead of reveal

Mercedes-AMG has revealed new details of the composite aluminium body shell used by the all-new SL roadster, due later this year.

Completely unrelated to the structures that underpin the previous-generation SL and current AMG GT, the new body combines an aluminium space frame with a “self-supporting structure”.

Mercedes claims the development process was particularly challenging given this new SL features a 2+2 seating arrangement, and will accommodate a wider variety of powertrain options. The priorities, it says, were to “present the driving performance characteristic of the brand with a focus on lateral and longitudinal dynamics, as well as to meet the high expectations in terms of comfort and safety”.

A combination of aluminium, steel, magnesium and fibre composites was selected for the best balance of lightness and rigidity, with the new SL boasting an 18% increase in stiffness over the old model. Transverse rigidity, AMG claims, is up 50% over the AMG GT Roadster, while longitudinal rigidity has been boosted by 40%. 

The main body shell – without the doors, bonnet, boot lid and other exterior fixings – weighs 270kg.

Recently, the firm released images of the upcoming SL roadster undergoing winter testing, ahead of its official reveal in summer.

The reborn convertible will square off against the Porsche 911 Cabriolet with a range of hybridised straight-six and V8 engine options.

The images showed multiple SL variants side-by-side in minimal disguise, highlighting two different fabric roof options. This confirms Autocar’s previous reports that the SL will arrive with a traditional fabric hood in place of the folding hard-top arrangement that has been used for the past two incarnations.

Mercedes also confirmed that the 2+2-seat SL will be sold under the AMG brand only and will be offered with fully variable 4Matic+ all-wheel drive. While much of the SL’s development was handled virtually, final on-road testing will soon include the north loop of the Nürburgring, hinting at the car’s sporting ambition.

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The range is understood to start with an SL 450 EQ Boost model running a turbocharged 3.0-litre in-line six-cylinder developing around 365bhp, along with an added 22bhp in combination with an integrated starter motor.

Further up will be the SL 53, which will run a more powerful AMG-tuned version of the SL450 EQ Boost’s mild-hybrid drivetrain with around 430bhp and added 22bhp through electric assistance.

Among the V8-powered models will be the SL 500 EQ Boost. It is due to receive a turbocharged 4.0-litre V8 with a similar power output to the SL 53, but significantly more torque. Topping the range will be the SL 63. It is likely to be offered in two states of tune, with the most powerful model running a turbocharged 4.0-litre V8 capable of in excess of 600bhp and more than 30bhp of electric boost. It is unclear if Mercedes will continue with the V12-powered SL, although, given the potential output of the SL 63, it would seem unlikely.

All engines for the new SL will come as standard with Mercedes’ nine-speed automatic gearbox, with the AMG variants set to adopt the Speedshift electronics package for faster shift times. Suggestions are that Mercedes could offer 4Matic four-wheel drive alongside standard rear-wheel drive, although this has yet to be confirmed.

Despite the SL’s market repositioning, it won’t completely abandon the luxury focus, so expect the interior to be almost as opulent as Mercedes’ other high-end models. It will be more driver-focused than cars such as the S-Class Coupé, but there could still be plenty of the brand’s latest driver assist systems drafted in, including its semi-autonomous Drive Pilot function.

Additional reporting by Rachel Burgess