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Greater than the sum of its parts

Audi doesn’t have platforms any more. Instead, it is developing components that can be used often in different cars. It will develop future vehicles using the chassis as a base on to which the different components are added.

The advantages are considerable, says Arne Leetz, head of technical development. “The main advantage is in quality. If you use a component in multiple products then it’s safer for us and the customer. It’s an improved part.”

Moving to the component approach also has an effect on the chassis, says Horst Glaser, general manager for chassis development. “It was important to build up the car’s GT character,” he says. “That means good comfort but sporty handling and high-speed stability.”

One of the biggest changes came from creating a more precise steering feel. Normally the steering gear goes behind the axle, but on the A5 engineers were able to attach it in front. “This gave us the opportunity to introduce the steering forces directly from the wheel into the knuckle, as opposed to the upper end of the knuckle,” says Glaser.

Audi had to overcome some packaging issues. It moved the front axle 150mm toward the front and altered the layout of the drivetrain. “Normally you have engine, clutch and differential in a front-wheel-driven car,” says Glaser. “We switched the positions of the differential and clutch inside the gearbox. It gives much better front to rear load dispersion.”

Audi also looked closely at “brake-diving”. “We switched the rear axle’s virtual point of rotation,” says Glaser. “We moved it from beneath the rear axle to the front of the rear axle. It’s the only Audi where we’ve been able to do this.”

Audi believes the switch to component-based construction will provide a big pay-off for the A5 in the future, but there were unexpected challenges in development. “You have to develop components from new. That means investment in headcount. You also need a new gearbox and powertrain,” says Glaser. “But when you have components and can use them in other cars, development gets easier.”

Early in the A5’s development, Glaser’s team encountered a strange phenomenon that affected the ride comfort. Luckily this was just a result of using new components and, discovered at an early phase, it was relatively easy to resolve.

The A5 involved about 20–30 per cent more virtual development. “Every time you make a new product, you must do it in less time than before,” says Glaser. “Virtual development lets us try all the possibilities and then can choose more wisely.”

Audi says it is looking to increase its range – from 22 to 40 models by 2015 – and the rate at which it introduces models. Of the €11.8 billion earmarked for the expansion, €8.4 billion is designated just for new products.

Component-based construction will play a key role in making this possible. The A5 is clearly just the first step, but it is an important part of how efficiently the firm will be able to launch new vehicles and how successful the expansion will be.

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