Light-footed and agile: the running gear
The sporting talents of the new A4 Cabriolet are by no means limited to the drive train department. The lightweight aluminium suspension, based on the much-praised axle design of the new A4 generation, provides the ideal basis for maximum agility and, consequently, sheer driving pleasure.
Four-link front suspension and trapezoidal-link rear suspension enable maximum steering precision and clearly defined handling with excellent cornering stability. Ride comfort also benefits from this ingenious axle design because a low unsprung mass also makes for a particularly sensitive response.
This is a general characteristic for which the A4 saloon has already received unanimous praise in the automotive press, and which is accentuated even more clearly on this new model. Audi's development engineers have tuned the chassis components to improve sports performance even further. And they have also lowered the suspension - and consequently the centre of gravity - by 20 millimetres compared with the saloon and Avant models.
The rear suspension
Like the other versions of the Audi A4, the new Cabriolet generation comes as standard with one of the most complex and most efficient rear suspension systems currently available: the self-tracking trapezoidal-link rear axle.
The trapezoidal-link axle makes for top-quality ride comfort, coupled with the kind of dynamic performance that need fear no comparison with the competition.
The trapezoidal link is made from hollow-section aluminium. This torsionally and flexurally rigid control arm absorbs a large portion of the forces acting on the wheel. Together with the track rod located behind it, it determines the elastokinematic behaviour of the axle.
All wheel control elements pivot on the resiliently mounted subframe via rubber-metal mounts. These isolate axle vibration very effectively from the body. Moulded rubber mountings are also used for the coil springs between the trapezoidal link and the body's longitudinal member. Here again, the choice of material and design provides excellent acoustic insulation.
The twin-tube gas-filled shock absorber is connected to the wheel carrier so that a direct-ratio effect is obtained. Combined with the separately mounted spring, this ensures a particularly sensitive response from the shock absorber.
The front suspension
With its precise, comfortable steering characteristics and road behaviour, Audi's four-link front suspension layout set the standard compared with the competition. The advantage of this concept is that the steering axis - a virtual axis around which the wheel moves when turned - runs almost perpendicularly through the wheel's centre. This means that virtually no driveline influences are felt at the steering.
In the new A4 generation, Audi's suspension developers have now updated this highly advanced suspension concept by adopting numerous lightweight but very strong aluminium components.
On the four-link suspension layout, each wheel is located by four aluminium control arms. The swivel bearings are likewise now made from the same light alloy, a change which cuts weight by around 40 percent compared with the conventional version.
The subframe, on the other hand, represents the systematic application of lightweight steel design principles; the use of high-strength, thin-walled plates reduces the weight by around two kilograms.
Large-volume rubber components are used as the damper mounts on the new suspension design. This helps to isolate the shock absorbers acoustically.
The steering: precision and lightness
The new Audi A4 Cabriolet has hydraulically assisted rack-and-pinion steering bolted to the suspension-strut cross member.
The improvement can also be felt at the steering wheel: the driver registers this as greater precision and an even more spontaneous response to steering movements.
The six-cylinder versions of the new Audi A4 Cabriolet are fitted with damping valves integrated into the steering system. They reduce vibration of the steering wheel and its susceptibility to jolts as a function of steering-wheel angular velocity.
As with the entire running gear, the dictates of lightweight design even extend as far as the design of the steering wheels for the Audi A4 Cabriolet: for reasons of weight, the single-section skeletons are die-cast in magnesium.
Road behaviour: a policy of neutrality
Superb traction when coming out of even the tightest of bends; neutral, clearly defined self-steering characteristics and finally maximum agility - these were the main demands placed on the developers of the running gear for the new Audi A4 Cabriolet.
Such targets can only be attained by coordinating all elements to a high standard of precision. The role of the new self-tracking trapezoidal-link rear suspension in the overall package is of course particularly significant. Its elastokinematic steering properties promote above all the desired precision of response to effects on the steering, while significantly pushing back the handling limits.
On the circular test pad, the most revealing gauge of behaviour close to these limits, the Audi A4 Cabriolet needs only a slight increase in the steering wheel angle to remain on course at moderate to high lateral acceleration.
From the driver's standpoint, the effect is clear enough: the Audi A4 Cabriolet remains unruffled even when close to the adhesion limits, and stays on the chosen line with controllable and strictly neutral behaviour.
At the same time, body movements even in S-bends remain moderate, without any of the loss of comfort that might be expected from this dynamically firm layout. This is because the spring rate has been raised to boost roll stiffness considerably - a positive effect that is maintained in a wide variety of load conditions.
Like all Audi A4 models, the Cabriolet is also fitted with the latest Electronic Stability Program ESP as standard. The system helps the driver to remain in control in potentially critical situations at the handling limits.
Hydraulic brake assist is also a standard feature of the latest ESP generation on the Cabriolet. Its task is to help the driver in emergency braking situations by automatically increasing braking pressure. This helps to reduce stopping distance considerably in hazardous situations.
Audi also establishes a benchmark for this class with the new model's equipment specification. Features such as the fully automatic hood and the active, automatically triggered roll-over protection device are supplied as standard on the Audi A4 Cabriolet. The hood can be ordered in the colours black, blue or red as required.
The standard specification also includes the deluxe automatic air conditioning with sun sensor and separate temperature selectors for the driver and front passenger, together with fog lights, heat-insulating glass and variable-height front seats with easy entry function.
Other standard features include electric front and rear windows and central locking with radio remote control, which also locks the glove compartment.
The Audi A4 Cabriolet is fitted with 16-inch "7-arm" cast alloy wheels with 205/55 R16 (3.0: 215/55 R16) tyres. Over and above this specification, the top models with 3.0-litre engine have the Driver Information System DIS and a 4?spoke leather steering wheel as standard.
Each A4 Cabriolet has extensive storage space including drawers under the front seats and nets on the back of the front seats. The large load-through facility, another standard feature, can be used to transport skis or even two snowboards.
Anodised aluminium for the window capping strips, the cover on the hood compartment and the finish of the windscreen frame add sporty visual accents.
Comprehensive safety systems are a matter of course on an Audi Cabriolet. ESP with ABS and hydraulic brake assist, the Electronic Differential Lock EDL and Anti-Slip Regulation ASR guarantee maximum active driving safety. In addition to front airbags and head/thorax side airbags for the driver and front passenger, there are belt tensioners and belt force limiters for all seats. The Isofix child seat mounts on three seats mean that children can also enjoy open-air travel in safety. This is also the purpose of the standard function that enables the front-passenger airbag to be deactivated with the ignition key.
In addition to the generous standard specification, an extensive range of extras - from xenon headlights to the Audi telematics traffic service - offers numerous possibilities for customising every A4 Cabriolet to suit each customer's individual requirements.
A particularly popular feature among drivers of convertibles is a wind deflector, which effectively protects those travelling up front against air turbulence if the rear seat is unoccupied. If the wind deflector is not needed, it can be folded up and stowed compactly in the net on the luggage compartment bulkhead in the bag provided.
Comfort and driving pleasure can be enhanced with speed-dependent Servotronic steering (option). This regulates steering effort depending on speed. It conveys precise steering sensitivity with maximum feedback from the road at high speeds, and guarantees maximum possible assistance when parking.