The 3.0 V6
This is undoubtedly an appropriate top engine for such a dynamic and elegant convertible: the V6 with five-valve cylinder head develops 162 kW (220 bhp) from 2976 cc at 6300 rpm. Its peak torque of 300 Nm is available at 3200 rpm. It consequently accelerates the A4 Cabriolet with 5?speed manual gearbox from 0 to 100 km/h in 7.8 seconds, and on to a top speed of 243 km/h.
The average fuel consumption of this version is a mere 9.7 litres per 100 kilometres (1999/100 EC).
The supremacy of this engine is audibly expressed by its carefully tuned, sporty sound. And the new design of the engine compartment, signalling a departure from plastic-shrouded drive units, is a visual reflection of the advanced technical calibre of Audi engines.
The 3.0-litre V6 engine weighs in at only 163 kilograms. The decisive factor behind this radical weight saving was unquestionably the decision to use aluminium as the main material for the engine block.
The design of the 3.0 V6 was determined not simply by the demand for more power, but by the desire to create an even more refined engine. Its 90-degree layout is in any case among the smoothest-running available, as the free inertial forces are entirely in equilibrium in engines at an angle of 90 degrees.
The 3.0-litre V6 delivers both high torque at low engine speeds and free-revving right up to its rated speed. Camshaft adjustment plays an important part here: the inlet camshaft can be gradually advanced by up to 42 degrees; on the exhaust side, the camshaft can be retarded as necessary by up to 22 degrees. The system achieves maximum overlap at an engine speed of only 1900 rpm, thus guaranteeing the highest possible amount of torque. The peak level of 300 Nm is then available at as little as 3200 rpm. No less impressive: 90 percent of this peak torque is available right across a wide speed range, from 2200 to 5200 rpm.
In parallel with camshaft adjustment, there is also the newly developed two-stage variable-length intake manifold. From 4200 rpm, the resonance tube reverts to the short, high-performance position; the maximum output of 162 kW (220 bhp) is finally reached at 6300 rpm.
In addition to improved output and torque, camshaft adjustment means lower fuel consumption and fewer untreated emissions.
The exhaust emissions are treated by two underbonnet ceramic primary catalytic converters which, thanks to their high cell density and coating of three precious metals, light off very rapidly. The two main catalytic converters beneath the vehicle's body maintain the long-term stability of the emissions and optimum exhaust-gas back pressure. All transmission versions of the new 3.0 V6 engine are consequently able to undercut the tough EU4 emission standard.
The 2.4 V6
The other V6 engine that is available for the Audi A4 Cabriolet at launch, the 2.4?litre version, is also ideal for the task in hand. This proven power unit is notable in particular for its superlative power characteristic combined with an outstanding level of refinement.
Audi's engine experts have comprehensively revised this engine to prepare for its adoption in the A4 model series. The most significant change is that its power output has been boosted to 125 kW (179 bhp) and its torque to 230 Newton-metres. Its effect is impressive: the A4 Cabriolet with manual 5-speed gearbox and 2.4 V6 accelerates from 0 to 100 km/h in 9.7 seconds; the top speed is 224 km/h. And yet its overall fuel consumption is only 9.7 litres per 100 km (1999/100 EC).
The 2.4-litre engine's emission levels in the Audi Cabriolet are below the EU IV limits.
World first for a convertible: multitronic
The Audi A4 Cabriolet introduces a brand new dimension to transmission technology, unique in the convertible segment, in the form of the multitronic continuously variable transmission. This transmission combines the dynamic qualities of a manual gearbox with the convenience of an automatic. And the multitronic adds to these strengths with the unique experience of continuously variable acceleration.
A further fundamental advantage of the multitronic is the high spread of ratios. This means the difference between the largest to the smallest transmission ratio - 1:2.1 to 1: 12.7. With the spread in this instance more than 1:6, it is very close to the ideal value for a transmission. This on the one hand permits dynamic, sports-style acceleration thanks to the use of the highest possible ratio, and on the other hand maximises the engine's refinement by using the lowest ratio at low engine speeds.
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 A4 saloon, 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 added dynamism can also be felt at the steering wheel: a new steering valve clearly reduces the steering torque tolerance. The driver registers this in the form of greater precision, through an even more spontaneous response to steering movements.
The Audi A4 Cabriolet has damping valves integrated into the steering. They reduce vibration of the steering wheel and its susceptibility to jolts as a function of steering-wheel angular velocity.
Audi's developers have also achieved an optimum steering layout in terms of safety on the A4. Because the steering column is mounted in two universal joints, it can be disengaged in the event of a crash, to isolate it from the steering gear and bulkhead.
The dictates of lightweight design even extend as far as the design of the steering wheels for the Audi A4: for reasons of weight, the single-section skeletons are die-cast in magnesium.