Audi S4 Cabrio

Another Audi sports model with a strong personality is about to leave the starting grid: the Audi S4 Cabriolet. This car combines the qualities of the Cabriolet with the powerful V8 engine from the Audi S4 and the dynamic handling of the quattro driveline. Restrained visual changes underline its sports character.
Design and equipment

The new Audi S4 Cabriolet expresses its supremacy by adopting a deliberately restrained appearance. A closer look, however, reveals that this stylish, sporty body is indeed subtly different in its basic form and proportions from the other Audi A4 Cabriolets: the bumper has large air inlets, the xenon headlights have a titanium-coloured surround behind the glass and the outside mirror housings have been given an aluminium finish. A glance at the rear reveals the powerful exhaust tailpipes on both sides that are so typical of the Audi S models. The Audi S4 Cabriolet runs on 18-inch cast aluminium wheels of S design with 235/40 R 18 tyres.

Inside too, this Cabriolet is immediately identifiable as an S4. The instrument cluster has the grey dials that are characteristic of S models and special needles. There is a choice of carbon fibre, piano finish, brushed aluminium and birch wood for the inlays. The car's sporty character is emphasised by the three-spoke leather-covered sports steering wheel with S emblem. There are shift paddles behind the steering wheel on cars with the 6-speed tiptronic transmission.

The Alcantara/leather sports seats, which have a lumbar support, an adjustable thigh support and can be electrically adjusted in several directions, provide firm lateral support and excellent comfort on long journeys.

The V8 engine: a torrent of power

The Audi S4 Cabriolet's eight-cylinder engine develops 253 kW (344 bhp) at 7,000 rpm, and delivers a massive 410 Newton-metres of torque to the crankshaft at 3,500 rpm. Such impressive figures are a sure sign of the superiority of this large-capacity, naturally-aspirated engine. Possibly even more impressive than its peak power output is the immediacy with which it responds to every movement of the accelerator pedal, and its remarkable willingness to run freely up to high revs. The exhaust system produces a deep, sporty note, always present but never obtrusive.

2005 Audi S4 Cabrio Front Angle

The Audi S4 Cabriolet sprints from 0 to 100 km/h in only 5.9 seconds, and reaches a top speed of 250 km/h, at which point the governor cuts in smoothly.

The eight-cylinder engine surprises the onlooker in yet another way: it is shorter and more compact than any other engine of this type and size, measuring only 464 millimetres from front to back. Audi's engine developers achieved this by moving the chain drive for the camshafts and auxiliaries to the output end of the engine, thus reducing its overall length by 52 mm. The weight is also extremely low for an engine with eight cylinders, at only 195 kilograms. This has definite advantages in terms of the car's weight distribution and road dynamics.

Power is delivered to the 18-inch cast aluminium wheels via a 6-speed close-ratio gearbox of the latest model generation with a precise shift action and short lever travel. The selector mechanism is decoupled, which largely prevents load-reversal movements or vibrations from being transmitted to the gear lever.

Available as an optional extra, the 6-speed tiptronic transmission with dynamic shift program, additional Sport program and shift paddles on the steering wheel combines sports-style driving with the convenience of an automatic transmission and is therefore ideal for smooth, relaxed travel in an open car.

The sports suspension: aluminium makes the car agile

The lightweight aluminium chassis consists of four-link front and trapezoidal-link rear suspension, and is designed to ensure maximum steering precision and clearly defined road behaviour with excellent lateral stability. Ride comfort also benefits from this ingenious suspension design, since low unsprung weight makes the suspension more responsive to road-surface irregularities.

Like the S4 saloon and Avant, the S4 Cabriolet has firm sports suspension settings – an important precondition for agility and thus for pure driving pleasure.

The servotronic steering is a standard feature; it varies the degree of power assistance according to road speed, so that the correct combination of steering precision and light action is always obtained.

The quattro driveline: driving fun and ample traction

The new Audi S4 Cabriolet has quattro permanent four-wheel drive as a standard feature. It can therefore translate engine power into optimal progress in any conditions and exploit the dynamic potential of its aluminium chassis with a new degree of supremacy. In other words: driving pleasure in the purest sense.

The body: class benchmark for vibrational comfort

Even in the early planning stages, Audi's body developers worked systematically on the structure of the body and simulated its reaction to movements of the suspension and the mechanical assemblies.

The result of this development process is that no unpleasant levels of either high- or low-frequency vibration reach the passenger area on roads of any kind.

Even driving pleasure benefits from the body's high rigidity because the direct steering enables the S4 Cabriolet to be guided extremely accurately around corners. This is made possible by the special steering column connection that takes account of the vibrational behaviour that is specific to convertibles.

The steering column mounting has an additional support, with the module cross-member linked to the cross-beam below the windscreen – measures that are decisive in keeping vibration at the steering wheel down to the lowest possible level.

Measures designed to increase strength and rigidity also affect the choice of material grades and joining techniques. For instance, high-strength and ultra-high-strength panels account for more than fifty percent of the bodyshell's weight.

Optimised wall thickness in conjunction with improved-quality weld points help to boost the structural durability of the body significantly. The body is in addition reinforced by a rigidly bolted-on subframe at the front, with additional diagonal struts at the front and rear.

A high level of crash protection

The Audi S4 Cabriolet's A-posts are optimised in cross-section and contain high-strength reinforcing tubes – a most important safety feature if the car should roll over.

Sills with an optimised thickness and cross-section boost the occupant cell's strength and optimise occupant protection. High-strength tubes are also used in the seat structure, as a means of enhancing occupant safety in the event of a lateral collision.

The doors in particular have to be designed with safety in mind. In conjunction with structural reinforcements in the sills and a strengthening cross-member below the rear seat, special impact absorbing beams in the doors ensure a high standard of safety. Crash resistance, even in the side impact test against a post, is on the same excellent level as the S4 saloon.

Comprehensive safety

The comprehensive safety package contains seat belts with belt-force limiter and belt tensioner for all passengers, together with full-size front and side airbags. The side airbags integrated into the front seats are designed to protect the head and thorax.

If the car should roll over, an active roll-over protection system in the double rear bulkhead adds to the occupants' safety. In this case, two protective bars, controlled by sensors, are triggered behind the rear passengers within milliseconds. Together with the extremely rigid windscreen frame, they help to preserve survival space for all occupants if the car turns over.

The standard electronic stabilisation program ESP with hydraulic brake assist provides for maximum active safety.

More than mere weather protection: the hood

An electro-hydraulic hood, which closes at the touch of a button in under 30 seconds, is standard equipment on the Audi S4 Cabriolet. The button only needs to be pressed once to either open or close the soft top. The side windows move down and up again to aid the process, and in the Audi S4 Cabriolet there is no locking handle to be released manually or tonneau cover to be detached.

A lever in the boot raises or lowers the hood compartment, so that a much larger luggage space becomes available when the hood is closed.

A heated, scratchproof glass window is just one of the reasons why the Cabriolet's lined hood is entirely suitable for winter driving. It has three layers of cloth and is sewn to high standards of accuracy to ensure maximum occupant protection, resist climatic effects and provide a standard of acoustic insulation worthy of a premium car such as this.

The hood's linkage is barely visible when the hood is in the raised position; the tautness of the hood and the cushioning prevent any "tent ridge" effect. The shape of the roof as a harmonious component of the Cabriolet design is thus preserved at all speeds.

The hood is also completely smooth on the inside. Together with the high-quality appearance of the surface, this look underlines the luxurious overall impression conveyed by the interior ambience.

Source: Audi

Gallery: Audi S4 Cabrio (2005)