Crossing the Blues

Monday, January 14, 2008

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


Audi dynamic suspension

The Audi dynamic suspension in the new A6 Avant uses a technology which has already proven its sporting qualities under the most demanding and challenging conditions: the enhanced, Audi-typical four-link front suspension layout in combination with the self-tracking trapezoidal-link rear suspension adopted from the Audi A8 and Audi A6 saloon – a combination featured both on the front-wheel-drive and quattro versions. The main components are made of lightweight aluminium which makes a decisive contribution towards reducing unsprung masses.

Not only has wheelbase been increased significantly (by 83 millimetres) compared with the previous model, the car’s track at the front is also up by 72 to 1,612 millimetres and has been increased at the rear by 49 to 1,618 millimetres – dimensions which set a new benchmark in this class. Weight distribution between the front and rear axles has also been optimised.

On the road this means dynamic driving behaviour of the highest calibre. Clearly, features of this kind again place the new A6 Avant on the same level as the A8 which was so lavishly praised by the motoring press. Like the latter, the A6 Avant is the sportiest car in its class. This is also due in no small measure to the speed-dependent servotronic power steering featured as standard, supplementing the precise handling of the new A6 Avant with an even more sensitive steering response.

The front suspension

In relation to the passenger cell, the four-link front suspension of the new A6 Avant has been moved forward by 83 millimetres compared with the previous model, thus ensuring a far better axle load distribution with corresponding advantages in terms of driving dynamics. This change in proportions also looks good, making the front overhang far shorter and thus giving the entire car a much more compact appearance.

Weight-optimised components help to reduce unsprung masses: four aluminium wishbones of optimised design guide the wheel; the axle subframe is of sheet-metal construction, the upper bearing block is made of cast aluminium. The tubular anti-roll bar has also been constructed in accordance with the principle of lightweight design.

The entire kinematics and elastokinematics have also been redefined, for maximum dynamic behaviour and comfort. Lateral rigidity in particular has benefited from the precise further development of all link bearings. Larger rubber mountings on the subframe insulate the cabin from road impacts.

The steering

The new Audi A6 Avant comes as standard with hydraulic rack-and-pinion steering featuring speed-dependent power assistance, Audi servotronic. The development goal here was to provide the highest conceivable standard of sporty steering precision and improved steering comfort.

The refined servotronic system enables the driver to manoeuvre into parking spaces with a minimum of steering effort and maximum accuracy, as well as providing a clear response from the road at higher speeds. The system also offers a high level of sensitivity around the straight-ahead position and even more comfortable initial response behaviour.

The steering kinematics have been optimised in such a way that despite the longer wheelbase and driven front wheels, the car’s turning circle is no larger than that of comparable saloon cars with rear-wheel drive. The steering ratio is even more direct on the sporty 4.2 model.

The steering wheel of the new Audi A6 Avant is adjustable by 40 millimetres in a vertical direction and axially by 50 millimetres. Intensive detail work in the area of the steering column and the point at which it is connected to the body makes sure that vibrations at the steering wheel are suppressed almost entirely and are practically no longer noticed by the driver.

The launch of the new A6 Avant generation also hails the advent of the latest generation of steering wheels. The skeleton of the steering wheel, which is not visible to the driver, is made of diecast magnesium, a material combining very low weight with very high rigidity.

The three and four-spoke steering wheels are recognisable at first glance from the airbag cover which echoes the same characteristic trapezoidal shape as the single-frame grille.

Depending on the customer's personal taste, the steering wheel rim is available either in wood or covered in leather (standard). All versions of the steering wheel can be ordered as an option with multifunction buttons and steering-wheel mounted tiptronic shift paddles. The four-spoke multifunction steering wheel can also be ordered optionally with a heated rim which can be activated at a button on the steering wheel spoke.

The rear suspension

An outstanding technical achievement that already benefits drivers of the Audi A8 and the latest generation of the A6 saloon is now also being introduced for the new Avant: self-tracking trapezoidal-link rear suspension fitted on both quattro and front-wheel-drive versions of this car. Hence, all new Audi A6 Avant models come as standard with one of the most complex and efficient rear wheel suspension concepts currently available.

The trapezoidal-link rear suspension makes for top-quality ride comfort on all models, coupled with dynamic behaviour that will amaze the driver of many a competing model.

The trapezoidal link is a hollow shell structure made from high-strength sheet steel. This torsionally and flexurally rigid link absorbs a large portion of the forces acting on the wheel. Together with the track rod located behind it, it thus determines the elastokinematic behaviour of the axle. The track rod is a lightweight sheet steel structure.

All wheel control elements pivot on the resiliently mounted subframe via rubber-metal mounts which isolate axle vibrations very effectively. Four large, hydraulically damping mounts help to insulate the body against vibrations.

The linear, high-strength steel springs rest on both the body structure and the trapezoidal links. The twin-tube gas-filled shock absorber is connected to the wheel carrier, so that a direct-ratio effect is obtained. This ensures a particularly sensitive response from the shock absorber.

Spring travel on the new Audi A6 Avant has been increased compared with the previous model, above all in the interests of ride comfort. Directional stability on bumpy roads, however, also benefits significantly from this improvement.

In terms of kinematics, the trapezoidal-link rear suspension has been developed with the focus on its sporting characteristics, one of the key development goals of the new Audi A6 Avant. The precise reduction of bump toe-in as a function of spring travel improves the car's directional stability, steering precision, and handling. The entire construction is conceived to provide neutral, moderately understeering driving behaviour all the way up to a high handling limit.

Available as an option: adaptive air suspension

As on the Audi A8 before it, the new A6 Avant together with the A6 saloon can be ordered with adaptive air suspension as an optional extra. This sophisticated system ensures an even more refined synthesis of decidedly sporty handling characteristics and supreme suspension comfort. The integrated self-levelling function makes sure that the Avant always maintains the same ride height, regardless of load and driving style.

Even when stationary, the body of the A6 Avant with air suspension is 13 millimetres lower to the ground, thus enhancing its sporty appearance. In addition, the air suspension allows the speed-dependent lowering of the body – this change in ride height means a low centre of gravity and significantly increased directional stability as a result. At motorway speeds the lowering of the body also optimises the car’s aerodynamic properties and thus reduces fuel consumption.

At low speeds the adaptive air suspension establishes greater ground clearance if the driver so wishes. This is an additional bonus on uneven terrain.

A choice of three different characteristics ranging from very sporty to comfortable can be selected via the central Multi Media Interface (MMI) control element.

The automatic mode represents the perfect all-round setting. At speeds of more than 120 km/h, the body is lowered by 15 millimetres. The change in ride height first of all means a lower centre of gravity. At motorway speeds, the lower settings in addition reduce drag and therefore fuel consumption. If the driver slows down to less than 70 km/h, the air suspension raises the vehicle body again to its starting position.

Gentle compression and excellent long-distance comfort are the characteristics of the "comfort" setting. If the "comfort" mode has been selected, speed-dependent lowering of the body at motorway speeds is suppressed.

The performance in the "dynamic" setting is a match for steel-spring sports suspension. In the "dynamic" mode, the car's ride height is lowered permanently by 15 millimetres.

At low speeds the adaptive air suspension establishes greater ground clearance of 15 millimetres in the lift mode if the driver so wishes. This is an additional bonus on uneven terrain. At road speeds of more than 100 km/h, the vehicle is then automatically lowered to its standard height.

In all selectable ranges, the continuously variable dampers are in addition automatically adapted to the type of road and driving style. The classic conflict between sportiness and comfort is thus overcome.



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