New Audi A6 Avant - In Depth

Page 1 - Design
Page 2 - Engines and transmissions
Page 3 - Engines and transmissions (cont.)
Page 4 - The chassis
Page 5 - The chassis (cont.)
Page 6 - The body
Page 7 - Comfort and communication electronics
Page 8 - Comfort and communication electronics (cont.)
Page 9 - Standard equipment
Page 10 - Optional equipment

The technology

The new A6 Avant has adaptive air suspension air spring struts on the front wheels, with the air-suspension bellows arranged concentrically around the infinitely adjustable shock absorbers. The air-suspension bellows consist of a special, multi-layered elastomer material with polyamide axial threads to increase strength. The advantage of this design is that the thin-walled and consequently soft-rolling gaiters lend the new A6 Avant excellent rolling properties and make the suspension highly responsive to minor jolts.

On the rear axle, the air springs and controlled shock absorbers are separated from one another. The advantage of this configuration, as with conventional suspension, is that it allows a large through-loading width and thus helps to keep the floor in the luggage compartment low.

Thanks to its concept, air suspension provides a number of inherent advantages: the occupants benefit from a pleasant, smooth ride at all times, regardless of the load the vehicle is carrying. This is because extra air is pumped into the springs at high gross weights, and discharged again when the load is removed. The firmness of the springs thus adapts to the load situation at all times.

Brake system

The brake system is also matched to the power potential of the new A6 Avant models. Even the entry-level engine version comes with 16-inch brakes, the particularly powerful 4.2-litre eight-cylinder version features a 17-inch brake system. The front brake discs measure 314 millimetres in diameter on the A6 2.4 and 2.0 TDI and 321 millimetres on the 3.2 FSI and 3.0 TDI (A6 4.2 quattro: 347 mm). The rear brake discs have a diameter of 302 mm (A6 4.2 quattro: 330 mm).

Benefiting from these large dimensions, disc temperatures under high brake loads are reduced by more than 100o C, improving performance reserves still further.

The system is operated via a tandem brake servo. In conjunction with a piston diameter of 27 mm in the master brake cylinder, this gives the driver a sporty, firm feel at the brake pedal together with excellent controllability.

Safety as standard: new ESP generation

All new Audi A6 Avant models come with the latest-generation electronic stabilisation program, ESP 8, developed by Bosch. This system comprises ABS brakes with electronic brake-force distribution EBD and hydraulic brake assist which automatically increases brake power in panic-braking situations. Together with the yawing moment controller, the traction control system ASR and the electronic differential lock EDL provide the foundation for enhanced ESP safety.

At the same time, ESP 8 incorporates outstanding new or optimised functions.

The emergency braking function alerts vehicles behind to potential hazards by activating the hazard warning lights when the brakes are applied hard.

Understeering control has been further optimised: when the vehicle understeers, the system no longer brakes just the two wheels on the inside of the bend; the brakes are applied to individual or even to all four wheels simultaneously, depending on the situation.

Improved safety for vehicle combinations

Large cars like the A6 and A6 Avant are frequently used to tow trailers, such as horse boxes or boat trailers, for examples. Another new function is indispensable to safety in such situations: it is often the case that when travelling at cruising speed, even in straight line, the trailer starts to move slightly from side to side which can consequently build up into a dangerous swaying motion. The trailer stabilisation system uses the ESP sensors to detect any swinging of the trailer Ã¢â‚¬â€œ caused, for example, by a sudden evasive manoeuvre by the driver or a crosswind. By applying the brakes automatically and reducing torque, the system decelerates the trailer, thus helping to stabilise it.

The new ESP has been advanced to an even higher standard in terms of both electronics and hydraulics. New pressure control ensures even more precise intervention of the ESP stabilising functions in accordance with the given situation, particularly when the car is understeering.

The brake disc cleaning function integrated in ESP is another new feature. This helps to keep the brake discs largely dry on wet roads, even if the driver has not braked for a long time. To achieve this, the brake pads are pressed against the discs under low hydraulic pressure at regular intervals, ensuring even more spontaneous brake response even in wet conditions.

For the first time the new Audi A6 Avant is fitted with a two-stage ESP deactivation button: pressing the button briefly deactivates the traction control system ASR only. This is sometimes necessary in order to be able to pull away in deep snow or on gravel roads. If the button is pressed a bit longer, on the other hand, the driver is able to deactivate ESP in all operating conditions. This is necessary on the race track, for example, to enable an intentional sideways slide through the use of the brakes. Even then, however, the EDL and ABS functions remain operative.

Electromechanical parking brake

Following its successful debut in the Audi A8, the electromechanical parking brake is now also being introduced in the new A6 Avant, offering significant functional advantages over and above all the usual functions of a conventional handbrake.

The system, operated via a pull/push control on the centre console, automatically ensures the necessary parking brake application force. The operating concept is deliberately based on what most drivers would consider the usual operating principle for conventional systems: a quick pull of the switch applies the brake; if the driver pushes it down Ã¢â‚¬â€œ while the brake pedal is depressed Ã¢â‚¬â€œ the system is released.

The parking brakeÃ¢â‚¬â„¢s status is indicated by tell-tale lights in the control element and in the instrument cluster.

The system is designed for gradients of up to 30 percent. If this is exceeded, the driver is warned by a text message (Ã¢â‚¬Å“vehicle too steepÃ¢â‚¬Â').

Moreover, by way of an integral starting assist function, the electromechanical parking brake makes it easier to pull away without jolts or rolling backwards on inclines, without the driver needing to release the brake by hand. The system calculates the ideal moment for releasing the parking brake, on the basis of data such as the transmission position selected, the accelerator pedal position, engine speed and the angle of inclination. On cars with a manual gearbox, the system also takes the position of the clutch pedal into account. As soon as there is sufficient torque to move the vehicle forwards, the electronics automatically release the parking brake.

It goes without saying that the electromechanical parking brake also has the emergency braking function stipulated by law: above a speed of 8 km/h the driver can stop the vehicle simply by pulling on the switch Ã¢â‚¬â€œ if the brake pedal locks, for example. Within barely more than a second, this builds up a deceleration force of 8 m/s2, far more than with a conventional handbrake.

Wheels and tyres

Even the four-cylinder and six-cylinder versions (up to 130 kW) of the new Audi A6 Avant come as standard with 7x16-inch alloy wheels shod with 205/60 R16 tyres. The particularly powerful six-cylinder models ride on 7.5x16-inch wheels with 225/55 tyres, the 4.2-litre eight-cylinder model is fitted as standard with 17-inch wheels on 225/50 tyres.

As an option, the new Audi A6 Avant is available with a choice of ten different versions of wheel up to 18 inches in diameter and running on tyres up to 245/45 R18. In winter, A6 drivers have the choice of three wheels up to 7x17 inches in size and fitted with 225/50 tyres.

All new Audi A6 Avant models come as standard with the Audi tyre mobility system, but may also be supplied with a spare wheel as an option.

A permanent tyre pressure monitoring system is also available as an option for the new Audi A6 Avant. The system monitors the tyre pressure and temperature of each individual wheel.

In the event of a loss of pressure, it informs the driver optically and acoustically via the display in the instrument cluster, indicating the wheel involved. To provide this function, the signals from the wheel's electronic control unit are transmitted wirelessly to the central vehicle electronics.

There are two warning stages: a pressure loss of more than 0.3 bar at a wheel activates a yellow warning lamp. This tells drivers to check their tyre pressure and top up the air to the correct level at the next opportunity. If tyre pressure is more than 0.5 bar below the limit required or if the tyre is losing pressure quickly, a red lamp lights up urging drivers to stop immediately and remedy the problem.

The system is also able to take into account minor changes in temperature and pressure caused, for instance, by intense sunshine, hot air coming from the engine or unusual weight distribution of the car, thus avoiding any false alarms.

As an option: PAX wheels

From 2005, the new Audi A6 Avant will also be available with cast aluminium wheels with run-flat tyres Ã¢â‚¬â€œ the so-called PAX system. These wheels and tyres allow drivers to continue for up to 200 kilometres at a top speed of 80 km/h, even if a tyre has suffered a complete loss of pressure.

Thanks to the run-flat properties of the PAX wheel, drivers can, in the event of a puncture, reach an Audi workshop of their choice instead of having to change the wheel themselves or call a breakdown recovery service Ã¢â‚¬â€œ a new dimension to mobility that befits the executive segment.

The flat tyre still offers a high level of residual ride comfort Ã¢â‚¬â€œ driver do not perceive a loss of pressure as a permanent deterioration of running characteristics. However, to make drivers aware of the threat of a flat tyre or a gradual loss of pressure, the PAX system is only offered in combination with the automatic tyre pressure monitoring system.

This means that drivers are kept informed of the condition of all wheels and are in addition reminded of the maximum permitted speed of 80 km/h if one of the tyres suffers a puncture.

The PAX system consists of a special wheel rim, a modified tyre design and the actual run-flat element, a support ring that sits almost in the middle of the rim and encloses it. This technology ensures the tyre's run-flat qualities even if there is a complete loss of pressure.