Audi launches quattro Ultra
BY DANIEL GARDNER | 30th Mar 2016
The quattro Ultra system will debut globally under the 2016 A4 Allroad quattro this month and in Australia during the third quarter of this year, but will be rolled out for more longitudinal engine models over the following months.
Like many other brand's all-paw approaches, the quattro solution allows the rear pair of wheels to freewheel when maximum four-wheel traction is not required, but Audi says the crucial part is how and when the Ultra technology decides to engage and disengage the rear axle.
The system requires the ability to engage and disengage the rear axle rapidly and Audi's solution uses an oil-immersed multi-plate clutch pack connecting the transmission to the tailshaft, which responds quickly to changes in drive requirements.
However, a second decoupler clutch is located in the differential at the other end of the shaft, which disconnects the significant rotating mass from the rear wheels when not required, boosting efficiency.
Efficiency gains of up to 0.3 litres per 100km are possible thanks to the drag reduction says Audi, but a reduction of 4kg over the previous longitudinal quattro system also improves economy and handling characteristics.
By incorporating a variety of new vehicle data, the system can also spend more time driving only two wheels for improved fuel consumption, but the same advancements have also allowed the engagement of all four wheels faster – in most cases before wheel slip occurs.
Audi says the Ultra layout operates in three different states: In proactive mode the system is more akin to existing technology, using vehicle data from various sensors to detect if a wheel is about to lose traction and can introduce additional rear drive 0.5 seconds before the limit is reached.
In predictive activation the system monitors the driver's behaviour as well as the various sensors to predict the limits of traction before they are exceeded, which can provide a more accurate and intuitive response.
The third reactive condition intervenes with four-wheel drive under circumstances when a sudden change in conditions and subsequent grip reduction can not be predicted, such as mid-corner ice.
Driver behaviour observation is managed partly by the Audi Drive Select system that allows a driver to tell the vehicle how it is going to be driven, and the predictive software can better prepare for quattro Ultra system activation.
Audi says the Ultra system is intuitive enough to allow pure front drive even when on deep snow, provided only low torque is required and in a straight line, but can deliver rear-torque as soon as conditions change. The system is equally as adaptable during fast driving and in good conditions as well, the car-maker says.
Audi's S tronic automatic transmission and manual gearboxes will provide the gear sets, while the 2.0-litre TFSI four-cylinder will be the first engine to drive the system, but is expected to be joined by others as new models adopt the Ultra system.
