Directional input

The new Audi A8 and the Audi A7 Sportback (soon to be released in Australia) are large, luxurious grand tourers. Each boasting spacious and beautifully appointed interiors, they represent the ‘big end of town’ and for passengers, they offer the very finest in interior accommodation.

But where in the past, that overall size might impact on manoeuvrability in tighter spaces, with Audi’s new option of dynamic all-wheel steering, the manoeuvrability at low speeds and in tight spaces is not an issue.

Not only that, but the systems also makes for even greater stability at speed, thanks to the marriage of two high-tech steering systems working together.

Put simply, at low speeds – say in a parking garage or turning around in a narrow street – the rear wheels turn in the opposite direction to the steering input of the front wheels, which results in a greatly reduced turning circle.

At high speeds, the rear wheels turn in the same direction as the front, thus providing greater vehicle stability.

For those who like their technical information slightly more technical, 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. That translates to 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, making it easier to manoeuvre and reducing the turning circle by around one metre – no small amount on a vehicle like the A8 which is five metres long. 

At medium and high speeds, they turn with the steering direction by up to two degrees, which raises stability and allows the large sedan to handle even an abrupt lane change smoothly and serenely.

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 stabilises the car with the aid of steering interventions at the front and rear axles.

The result of all this wizardry going on out of sight, is extraordinary manoeuvrability in tight spaces, and handling ever on the tightest switchbacks that belie the size of the vehicle. Effectively, in the twisty stuff, the large, luxury sedan ‘shrinks’ around the driver and takes on the agility of a small, sports car.

The very best of all worlds.