Perfectly dimensioned for four people: the spacious interior
The occupants of the Cabriolet are treated to very high class travel, in terms of both safety and the available space inside the car. The wheelbase has been increased by 100 millimetres compared with the previous generation.
This means considerably more room in all directions; the A4 Cabriolet is a full-size four-seater vehicle. 66 millimetres more knee room for the rear passengers, 33 millimetres more shoulder room at the front and as much as 52 millimetres in the back: these are just some of the figures that verify the quantum leap between generations and that are confirmed by a generous feeling of space which can also be felt subjectively.
There is also considerably more luggage capacity than on the previous model: thanks to the variable design, 315 litres are available when the hood is closed - enough for two golf bags. There is still 246 litres of space with the hood down. A dimension that puts the Audi A4 Cabriolet clearly ahead of key competitors.
A standard load-through facility to the passenger area also increases the variability of the luggage compartment. Its cross-section of 190 x 280 millimetres provides enough space for up to three pairs of skis or two snowboards.
Not even the optional wind deflector takes up much space in the luggage compartment if not needed. Thanks to an ingenious design it can be folded up to hardly more than a quarter of its size and stowed compactly in the luggage compartment in its own bag.
The new Audi A4 Cabriolet also sets the standard in its class with a tank volume of 70 litres.
Powerful and refined: the engines
Two powerful V6 engines will provide the Audi A4 Cabriolet from launch with a level of propulsion befitting its class: the new 162 kW (220 bhp) three-litre V6 with aluminium engine block and continuous camshaft adjustment and the 2.4-litre version boosted to 125 kW (170 bhp) will be available at market launch. With a peak torque of 300 or 230 Nm respectively, they make supreme traction from any speed as much fun as swift acceleration from a standstill.
At the same time, both V6 engines are notable for their sporty six-cylinder sound and outstanding refinement - a combination that is extremely popular, especially with drivers of convertibles.
Both engines in combination with each driveline version comply with the strict limits prescribed by the EU4 emission standard.
The 3.0 V6
This is undoubtedly an appropriate top engine for such a dynamic and elegant convertible: the V6 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 composed, 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 design of the three-litre unit was determined not simply by the demand for more power, but also 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 in equilibrium.
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.
At just 1900 rpm the system switches to maximum valve overlap in order to achieve the highest torque possible: as a result, 90 percent of peak torque is available in a wide speed range between 2200 and 5200 rpm. And equally as impressive, the peak value of 300 Nm is reached at just 3200 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.
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 engine is notable in particular for its superlative power characteristic combined with an outstanding level of refinement. Audi's engine experts have comprehensively revised this tried-and-tested engine to prepare for its inclusion in the A4 model series.
It now has a maximum power output of 125 kW (170 bhp) and a peak torque of 230 Nm. 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. This contrasts starkly with an overall fuel consumption of just 9.7 litres per 100 km (1999/100 EC).
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 automatic transmission. This transmission combines the dynamic and economical 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.
The revolutionary multitronic can be combined with all current engine versions of the A4 Cabriolet. This makes it possible to cover a broader power spectrum: the multitronic can now even transmit torques of 310 Nm. Even the most powerful petrol engine available for the A4 series, the 3.0 V6 with 220 bhp and a peak torque of 300 Nm, is available with multitronic.
An infinite number of transmission ratios
So how does this revolutionary drive concept work? On all previous transmission types, whether manual or geared automatic transmission, specific transmission stages are physically present inside the transmission casing, in the form of five, six or more pairs of gears or planetary gear trains. On the continuously variable transmission, on the other hand, there is just one pair of sturdy gears with a flexible transmission belt, which permits an infinite number of transmission ratios.
This central component is known as the variator: a transmission element resembling a V-belt connects two axially adjustable sets of pulley halves. By adjusting the spacing between them in line with the circumference of the tapered pulley halves, the transmission ratio of this belt drive arrangement can be varied across a wide range.
Instead of the mesh belt that is otherwise commonly used on CVTs, Audi has opted for a link-plate chain made entirely from steel, but which is nevertheless almost as flexible as a V-belt.
It is sufficiently strong to be able to transmit much higher torques and forces than thrust belts. In tests extending over a number of years, this type of chain has proven extremely reliable and guarantees lifelong durability.
It consists of several metal links which are connected by steel pins. Their face ends press against the tapered surfaces in the variator. The chain's tension is transmitted to the variator pulleys at these points of contact.
One fundamental advantage of the variator in 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.
This relationship of over 1 to 6 is close to the ideal value for transmissions. This on the one hand permits dynamic, sports-style acceleration thanks to the use of the highest possible ratio, and on the other hand fully exploits the engine's potential for economical operation by using the lowest ratio.
Instead of using the hydraulic torque converter that is fitted on other CVTs to handle the tasks of pulling away - inevitably incurring some degree of loss in the slip phase - Audi has opted for an electronically controlled, oil-cooled multi-plate clutch.
In addition to its improved efficiency, this type of clutch permits a wide range of starting characteristics. In other words, the multi-plate clutch can be controlled in such a way that every conceivable form of pulling away is possible, from an ultra-gentle edging along on a slippery surface to sports-style acceleration at full throttle.
The electronics detect from the way the accelerator pedal is being operated whether the driver prefers an energy-conscious or performance-oriented style of driving, and either adapt the engine speed very gently, or push it into the peak engine torque range as rapidly as possible. The electronic-control clutch can even implement a warming-up program to bring the catalytic converter up to temperature more rapidly, with temperature-dependent speed increase upon clutch engagement.
A further special feature is the ability of the electronics to emulate the functions of a manual gearbox. Audi has opted for six forward speeds, which can be selected by the driver with a single touch of the selector lever in the second gearshifting plane, or activated at the push of a button on the steering wheel (optional extra).
These six speeds are stored as fixed gearshift programs. Depending on which speed the driver selects, the controller is supplied with the ratio as a setpoint, which it establishes at the variator and maintains.
Even these manually prompted gearshifts take place with pleasing smoothness and jolt-free, without any interruption in traction, all the while satisfying the desire for sports performance thanks to their continuous adaptation.