By 2015, Audi's lineup from the A4 upwards will all have switched to lightweight aluminum construction, according to Autocar. That leaves only the A3 and A1 families that will be based on conventional steel monocoque chassis. The shift to hybrid aluminum construction will be made immediately on the next-generation A6 and A4 models, after rolling it out on the next A8.
Be on the lookout for the third-generation A8 flagship to be shown later this year. It will pioneer the new hybrid aluminum construction techniques that will allow Audi to use the lightweight metal for high volume production. The new A8 structure uses new construction and manufacturing methods that are also utilized for models lower down the range.
The structure consists of large aluminum castings for key areas including the front and rear chassis legs, the front suspension mounts, the base of the A-pillar and the front section of the transmission tunnel.
The new A8's rear chassis leg is said to be the largest diecasting in the world at 1.4 meters long. The A8's door structures, which are cast in one piece, are crucial for safety and can apparently be used to underpin all Audi models based around longitudinal engines.
Inexpensive aluminum extrusions are used on the rest of Audi's new body structure (including the sills, roof structure and floor sections).
These extrusions can be easily cut and bent to size. Audi engineers have incorporated additional materials to the new A8's hybrid aluminum platform. Making up the car's B-pillars are monolithic plate steel, which when heated up becomes floppy and can then be stamped into shape.
Audi engineers are then enabled to design a B-pillar that has varying wall thickness without going to the expense of using tailored blank sheet steel. For the new A8's bonnet and boot lid, Audi is expected to use lightweight carbon reinforced plastics, which allows complex shapes to be made in a single molding.
The material is already used for the Lamborghini Gallardo deck lid and will be used for the upper rear wing of the Audi R8 convertible. Moreover, thin-walled magnesium castings will be used for the A8's engine cradle. All of these technologies will be applied in the next-generation A6, A4 and upcoming A7 models.