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Tech News

Breaking the limits

Sporty handling with maximum safety – Audi brings together these two previously irreconcilable contradictions in the new A8 with the optional brand-new dynamic all-wheel steering, which combines two hi-tech steering systems.

Text: Johannes Köbler
Illustrations: postproductions technic GmbH

At the front axle is a dynamic steering system with a wave gear set that varies its ratio depending on driving conditions. The combination of the dynamic steering at the front axle and the rear-axle steering alters the overall steering ratio within a range from 9.5 to 17.0 – direct at low speeds and stable at high speeds. The rear wheels are angled via an electric spindle drive and two track rods. At low speeds, they turn against the steering direction by up to five degrees, thus making it easier to maneuver and reducing the turning circle by around one meter. At medium and high speeds, they turn with steering direction by up to two degrees, which raises stability. The large sedan handles even an abrupt lane change smoothly and serenely.

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Opposite-direction steering

The rear wheels steer in the opposing direction for better maneuvering at low speeds.

The dynamic all-wheel steering pushes at the very edges of physical feasibility because it makes it possible to set the steering angle of the front and rear axles fully independently of one another. It unites direct, sporty steering response with refined stability, thus addressing a long-standing conflict of interest. Dynamic all-wheel drive is incorporated into the Audi drive select handling system, where its characteristics and ratio can be regulated in three stages. It takes its commands from the electronic chassis platform (EFP). At the limits of the handling envelope – during understeer, oversteer and load shifting – or on road surfaces that are slippery on one side, it stabilizes the car with the aid of steering interventions at the front and rear axles.

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Same-direction steering

The rear wheels steer in the same direction for better stability at medium and high speeds.

Dynamic all-wheel steering –
system overview
In the new Audi A8 flagship, the electronic chassis platform (EFP) controls three mechatronic steering elements.

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Fuel consumption of the model named above:

Audi A8: Combined fuel consumption in l/100 km: 7.8 – 5.6 (30.2 – 42.0 US mpg); Combined CO2 emissions in g/km: 178 – 145 (286.5 – 233.4 g/mi)

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