The new Audi A4 Avant remains faithful to the manufacturer's best tradition of safety. According to crash tests with the new A4 saloon, this model line is one of the safest automobiles in Europe.
The test staff of Germany's Auto Bild magazine stated after the frontal offset crash test at 64 km/h that "these are the lowest load values ever measured by Auto Bild. Due to the perfect combination of the vehicle structure and the restraint systems, all load values are in an acceptable area."
This result is complemented by the latest success for Audi in the Euro NCAP crash test ("The A4 is a very safe car"). During this test, the A4 set new standards especially for the feared side post impact, where the occupant cell is subjected to extreme load. A safety feature that contributed greatly to the A4's positive result was the SIDEGUARD head airbag system. According to the German automobile club ADAC, which co-organized the test, "the saloon's head injury figures are impressively low."
A rigid passenger cell with clearly defined deformation properties provides the basis for effective occupant protection in the Audi A4 Avant. The most important components in the composite cell are the new front-end and floor pan concept and the large-area bumper cross-member. The latter ensures an even distribution of loads, even in an offset crash.
The design of the sills, using an integral aluminum extruded section, and the A-post, results in a sturdy side-panel frame.
Particular attention was devoted to the footwell's behavior in a frontal crash, especially with regard to possible intrusion. The driver's legs are also well-protected in the new A4 because the pedals are decoupled in a frontal crash and do not intrude further into the footwell. Additional energy-absorbing padding protects the feet against severe impact.
The safety steering column of the new Audi A4 also makes its contribution to frontal crash safety. Its components complement the protective potential of the seat belts and airbags. A telescopic mechanism and an additional system of joints mean that the steering wheel is by and large isolated from any deformation of the front bulkhead. The steering wheel and therefore the airbag too remain in their designated position in front of the driver.
Energy-absorbing cushions and load distributors cover the area beneath the steering column and the steering lock. In particular, they considerably reduce the risk of injury to the driver's knees.
The floor assembly, where large sills with an aluminum profile on the inner side and rigid cross-members divert or absorb impact energy, provides a safety basis in the event of side impacts. The crash-optimized B-posts using "tailored blank" technology also contribute towards stability. Even in a collision at 50 km/h in the Euro NCAP test, the side profile is only minimally deformed.
The seats also make a valuable contribution towards occupant protection. The front seats are integral steel structures with extremely rigid cross-bracing. They thus largely retain their shape in a side-on crash. This is of crucial benefit in keeping the survival zone intact.
The occupants are in addition protected by several side airbag systems. In the event of a side impact, remote sensors transmit signals which are compared with those from the sensor in the central airbag control unit. This concept enables all the side airbags to be triggered in accordance with the accident sequence.
The risk of injury to the torso and pelvic regions of the body in a side crash is above all reduced effectively by the thorax/pelvis side airbags integrated into the front seat backs. Rear thorax/pelvis side airbags are available as an option for the outer rear seats.
The head and neck regions benefit from SIDEGUARD, not just in this vehicle category a unique safety extra. This head-level side airbag system covers virtually the entire side window area, from the A-post to the C/D-post.
As well as improving the head injury criterion, SIDEGUARD also reduces the load on the neck, since movements of the head are much less severe. In offset crashes too, the head airbag reduces the risk presented by impact against the A-post.
Acoustic quality and minimum vibration
New developments for reducing the transmission of vibration which have already been used successfully on the A4 saloon and which include the re-tuned gearbox mounting at the body, are the basis for the A4 Avant's excellent refinement. The necessary synchronization of the cavity characteristics of the passenger cell and the dynamic body, door and lid properties were a special challenge to the interior acoustics experts.
In order to achieve an improved low-frequency interior noise level, Audi's engineers employed the latest methods of numeric acoustics simulation and compared them with actual measurements. The result: whereas in the past complex acoustic relationships could only be investigated by tests on the vehicle itself, good preconditions for freedom from vibration were achieved by carefully planned computer simulation during the A4 Avant's development.
As with the new A4 saloon, body rigidity of the A4 Avant has been increased significantly - for instance, torsional rigidity is up by 20 percent. A new body concept between the D-post and the rear roof frame, with large-surface profiles extending over the nodal areas, is particularly effective in increasing torsional rigidity.
Audi's engineers set themselves the demanding goal of achieving the same subjective noise impression for the Avant as for the saloon. Rolling, exhaust and airflow noises are suppressed efficiently by a new insulating concept for the rear body area.
Large molded absorber elements, well-planned ventilation and air extraction and the avoidance of airborne sound bridges in the body ensure an interior acoustic free from disturbing noises. As a vehicle with a large interior, the new A4 Avant was equipped with improved body soundproofing and fine-tuning of the powertrain mountings.
Aerodynamics and aeroacoustics
Despite the aerodynamic problems that the estate-car body style are bound to cause, the Avant's drag coefficient of cD=0.30 is lower than that of the previous saloon. The cD figure has been reduced by six percent compared with the previous Avant.
The quality of the aerodynamic shape was achieved by systematic design support at even early model development stages. The following areas were given priority:
The Avant also benefited from the progress achieved during joint development of the saloon. The aerodynamic underbody used for the first time on the A4 is an important detail that results from this work. The underbody trims offer significant potential for reducing air resistance and lift. Considerable detailed development was required when adopting these effects, as used in motor sport, on a production car. Development work with this much attention to detail could only be carried out in a wind tunnel that is unparalleled in the automotive industry - the one operated by Audi in Ingolstadt.
New technologies have permitted significant progress in aeroacoustics on the A4 Avant. The most striking example is the new duplex aerial, which has been optimized aerodynamically and aeroacoustically. An invisible but all the more effective example is the new A4 door sealing concept, which makes the Avant 3dB(A) quieter than its predecessor. To put this another way, isolation of the body against wind noise is twice as effective, and the A4 Avant has the same interior noise levels as the saloon.