Having familiarised itself with the use of structural aluminium while producing the hand-built SLS, Mercedes has taken the plunge by making the new SL its first series production car to be built predominantly from the stuff.
The state-of-the-art superstructure contains chill-cast, die-cast, stamped and extruded aluminium parts, as well as some magnesium and hot-formed galvanised steel. The components, joined using six different methods, contribute to a body-in-white weight 25 percent less than it would be in steel, along with a 20 per cent boost in static torsional stiffness.
Daimler’s determination to make this new SL worthy of the ‘Super Light’ billing has driven its engineers to find weight savings all over the car. Having taken 15kg out of the roof, 11kg out of the seats, 11kg out of the front suspension, 4kg out of the electrics, 4kg out of the stereo, 4kg out of the front brakes and even 250g out of the wheel nuts, they’ve delivered the SL500 at a claimed 1785kg.
Our SL 500 test car, brimmed and fitted with £19,000 worth of options, weighed 1815kg. Impressive, considering that most grand drop-tops comfortably exceed two tonnes. An entry-level Mercedes SL 400, by comparison tips the scales at 1735kg.
The car’s multi-link chassis is now almost exclusively forged aluminium and features valve-controlled adaptive dampers as standard. Those wanting a more sporting set-up can opt for the stiffer springs, dampers and anti-roll bars, and reduced ride height of the AMG sports package of our test car.
Mercedes’ Active Body Control suspension is also an option. It’s a self-levelling set-up that replaces the conventional spring struts and stabilisers with active hydraulic struts that continuously adjust in terms of spring length and roll stiffness. Contrary to popular misconception, air spheres are not involved.
Even after all that, the SL 500’s new aluminium V8 is far from overshadowed. At once 22 percent more fuel-efficient, 12 percent more powerful and with 32 percent more torque than the old SL’s normally aspirated 5.5, the new car’s 4.7-litre engine uses twin parallel turbochargers to produce 448bhp and a formidable 516lb ft.
It drives the real wheels through Mercedes’ latest 9G-Tronic Plus nine-speed torque converter automatic gearbox. Other engine options include a 3.0-litre V6, badged SL 400, an a pair of range-topping AMG-tuned models in the form of the V8 SL 63 and the V12 SL 65 AMG, both of which use an AMG-tweaked seven-speed auto transmission.