Audi A6
Continuing to challenge BMW and Mercedes-Benz in the executive segment means Audi has to reduce weight, use new manufacturing processes and bring in new technologies
- Published in Vehicle Development.
Full beam: LED headlights improve visibility, with a 5,500K colour temperature
Audi has had huge success in the executive car market. Since it introduced the A6 in 1990, the OEM has sold over three million units. If you include the Audi 100, the precursor to the A6, that number leaps to more than five million. And Audi wants to continue that success with its latest-generation vehicle.
But in the five years the new A6 – known internally as the C7 project – has been in development competition has grown considerably. BMW and Mercedes-Benz have already launched new versions of the 5 Series and E-Class respectively.
That made benchmarking more challenging for the development team, but targets for the new A6 remained the same: it had to be lighter, more efficient and satisfy customer demands for new technology.
Burkhard Wiegand, the technical project manager for the A6 sedan, says: “You don’t redefine the targets for development every time a new car comes out. You decide what behaviour and character you want the car to have and follow those targets.”
The key target for Wiegand was to make the A6 as light as possible. That’s difficult to achieve when cars are growing as customers and legislation demand the inclusion of more and more comfort features and safety systems.
But, while the latest generation of the A6’s wheelbase is 69mm longer than the previous generation at 2,912mm, overall length has decreased by 12mm to 4,915mm. It’s not a noticeable difference when you sit in the cabin but it has helped Wiegand and his engineers to reduce the kerb weight of the vehicle, which the OEM claims is up to 80kg lighter than the previous version.
The 3-litre TDI quattro variant has lost 40kg, weighing 1,720kg.
Some of that improvement has come from greater use of aluminium components, which Audi says accounts for more than 20% of the construction: the material makes up the cross-strut in the engine compartment, the cross-members behind the front and rear bumpers, and the suspension strut towers at the front of the car. The integral support frame behind the instrument panel, the rear shelf, the trunk bulkhead, the crossmember in the trunk, the front wings, the doors and the trunk lid are made of aluminium panels, as is the engine hood.
But greater diversity in material use caused challenges for the engineers: “You have to look at certain issues because often you can’t weld components together because there’s a problem with corrosion,” says Wiegand. That meant greater use of structural adhesives.
Where welding was required, Audi introduced diode laser technology to improve not only the manufacturing process, but quality. “If you weld something with solid-state lasers you can see the join. With diode lasers you can’t see the welding bead. That’s the result we wanted – it should look like a single part,” says Wiegand.
Diode lasers are used to braze and weld both aluminium and steel components. One area the technology is used in is to construct the doors: 12 lasers make 50 weld seams per door.
