Rigid structures: the body
This concept is ideally complemented by the high torsional rigidity of the Cabriolet. It is a full 112 percent more rigid than its predecessor - a quantum leap. This gain benefits both dynamic performance and comfort.
From the very outset, Audi's body specialists sought to create a characteristic that would represent the optimum in terms of both static and dynamic rigidity, and would be as close as possible to that of the saloon.
This objective has affected the choice of material grades and joining techniques. For instance, high-strength and ultra-high-strength panels account for around fifty percent of the bodyshell's weight. Optimised wall thicknesses in conjunction with improved-quality weld points help to boost the structural durability of the body significantly.
The lower rigidity that is inevitable on a convertible compared with vehicles with a permanent roof could be compensated for on the Audi A4 Cabriolet by an optimised bodyshell structure. The body is in addition reinforced by a rigid bolted-on subframe at the front, with additional diagonal struts at the front and rear.
The A-post - which plays a particularly vital part in a roll-over - is reinforced ultra-efficiently. High-strength reinforcing tubes and the generally optimised design of the posts assure the desired properties.
Sills with an optimised thickness and cross-section boost the occupant cell's rigidity and optimise occupant protection. High-strength tubes are also used in the seat cross-member, as a means of enhancing occupant safety in the event of a lateral collision.
The doors, too, perform a very special safety function on this model; their mere dimensions highlight the differences compared with the smaller doors on the four-door A4 saloon and Avant models. In conjunction with the structural reinforcements in the sill and in the side section beneath the rear seats, the special impact members in the doors have a particular safety function.
And at the car's rear end, the double rear wall improves the rigidity of the body. The roll-over protection element integrated into the double rear wall also benefits occupant protection.
More than mere weather protection: the hood
The Audi A4 Cabriolet has an electro-hydraulically operated hood that opens entirely automatically at the push of a button - a process that takes barely half a minute and is the ideal way to enjoy the sun and open-air driving.
When the hood is being opened, the lid of its storage compartment cover behind the rear seats is raised, and the hood is folded away out of sight. The lid then folds down flush with the body, so as not to interfere with the dynamic shoulder line of the A4 Cabriolet.
The Cabriolet hood is also perfectly equipped for winter-weather use: it has a heated glass window, and its triple-layer structure and accurate fit shield the interior effectively against both adverse weather conditions and exterior noise. 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 objective of Audi's developers was to create a passive safety concept that is on a par with that of the A4 saloon. The latter model has already demonstrated in impressive style just how effective its safety system is in several crash tests, including the Euro NCAP test for which it was awarded four stars.
The comprehensive safety package contains seat belts with belt-force limiter and belt tensioner, together with full-size front and side airbags. The side airbags integrated into the front seats are designed to protect the head and thorax.
An active roll-over protection system provides additional safety if the car overturns. 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 the survival space both for the front and rear passengers if the car rolls over.
The Electronic Stability Program ESP with hydraulic brake assist provides for maximum active safety.
Perfectly dimensioned for four people: the spacious interior
The occupants of the Cabriolet are treated to a very high standard of 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.
The luggage compartment has also grown considerably compared with the previous model: thanks to its variable design it has a capacity of 315 litres when the hood is closed, and still a generous 246 litres with the roof open - a dimension that puts the Audi A4 Cabriolet streets ahead of key competitors.
The new Audi A4 Cabriolet also sets the standard in its class with a tank volume of 70 litres.