Mercedes-Benz has promised us, before the end of the year, an all-new SL roadster made, for the first time, almost entirely from aluminium - in fact, only the A pillars and the frame of the fabric roof will be made of steel, to provide optimum roll-over protection.
And even that has been compensated for by making the rear panels out of even lighter magnesium alloy.
The slide-rule boffins say they've managed to make the new body shell 110kg lighter than a similar body in welded sheet steel - and the whole car will be 140kg lighter than its predecessor.
The designers have taken meaning of the letters 'SL' - sporty, lightweight - very seriously. Reducing weight was a major goal in developing the new two-seater - as was the case with its namesake, the original SL of 1954.
The new SL body is also appreciably stiffer than a comparable steel shell, thanks to the versatility of aluminium. Steel bodies are made of various thicknesses of sheet material, bent or pressed into shape and welded together, whereas the new SL body components are chill-cast, vacuum die-cast, extruded or pressed in sheet (depending on the application) and MIG welded, bent over, glued, bolted, riveted or friction-welded together.
Mercedes claims that the firewall is in fact the largest aluminium casting currently used in the auto body industry.
The main floorpan is a three-layer shaped panel welded up from hollow extruded sections, the door sills are 1.7-metre, seven-chamber extruded sections, providing exceptional lateral stiffness and protection in case of a side-impact collision, while the floor of the rear section is a hollow chill-cast section filled in with sheet-metal panels
The result is a very stiff, light, corrosion-resistant structure that's also quieter because aluminium doesn't 'ring' like steel - and the designers took that a step further.
They used the hollow sections ahead of the cast firewall as resonance spaces for large bass speakers, bolted into openings in the footwells, calling the system, simply, front bass.
And because the bass component of the music, which is normally lost in the wind roar, is now coming from a pocket of still air around the occupants' feet, the new SL has concert-quality sound even with the top down!
One of the less-publicised characteristics of a roadster is that washing the windshield with the top down usually results in an impromptu shower for the occupants - so the detail freaks at Mercedes-Benz built channels into the wiper stems to take water directly to the blades.
Special micro-slots in the blade-holders spray water only on the side of the blade ahead of its movement, not behind, so the occupants never actually see the water as the blade sweeps across it, and the water spray never disrupts the driver's vision.
The screen just magically seems to clean itself as the wiper blades move across it. A control unit linked to the car's aircon system adjusts the water flow according to ambient temperature and whether or not the roof is down - and uses radiator heat to preheat the wash water in winter!
And, because there's no splashing, the system uses about half the volume of a conventional washer, so the reservoir in the engine compartment needs to hold only 1.7 litres of water, saving a little more bulk and weight.
The devil is in the details, they say; the guys at Mercedes seem to be taking that very seriously indeed. We'll bring you more details on the new SL as they are released.