The Audi A4 is a stately mid-size car. The Sedan and the Avant measure within 2 millimeters (0.08 in) of one another. Both are 4.70 meters (15.42 ft) long; the allroad quattro measures 4.72 meters (15.49 ft). The Sedan and Avant are 1.83 meters (6.0 ft) wide versus 1.84 meters (6.04 ft) for the allroad quattro; height is 1.42 meters (4.66 ft), 1.44 meters (4.72 ft) and 1.50 meters (4.92 ft) for the Sedan, Avant and allroad quattro, respectively.
The body of the A4 showcases a classic Audi strength – the intelligent hybrid construction with high-end materials. The crossmember behind the front bumper, for instance, is made of aluminum. Conventional deep-drawing steel accounts for only 38 percent of the weight of the sedan. High-strength grades account for 32 percent and ultra-high-strength steels for 18 percent. The remaining 12 percent are hot-shaped steels, which get their extreme tensile strength from a dramatic temperature increase during shaping.
Hot-shaped steels account for 34 kilograms (74.96 lb) of the weight of the body-in-white of the Audi A4. Thanks to their relatively low wall thicknesses, they save nine kilograms (19.84 lb). Used at the frontwall crossmember, the center tunnel, the B-pillars and the inside sills, hot-shaped steels form a strong structure in the occupant cell. In a crash, they transfer the forces in such a way that the dissipation of energy poses the least possible risk to the occupants.
Audi uses a special structural adhesive in many areas to assemble the body. 95 meters (312 ft) of bonded seams overall further enhance the rigidity of the joint. In the doors and at the sills, another high-end technology is used: remote laser welding. An invisible seam produced by plasma brazing joins the side of the car to the roof. This seam is extremely precise and thus virtually invisible, so that the A4 does not need roof trim strips.
The low weight of the body is the foundation of the ultra-lightweight construction concept of the A4. Equipped with the 1.8 TFSI, the Sedan has a curb weight (without driver) of just 1,430 kg (3,152.61 lb). The body also achieves excellent values for rigidity, vibrational comfort and crash safety.
The restraint systems of the A4 are precisely coordinated with the deformation properties of the sheet metal. When activated in the event of a crash, the retention system considers the seating position of the driver and front passenger so that persons of all sizes are well protected. The system also includes standard side airbags in the front (optional in the rear) and head airbags.
The integral head restraint system diminishes the risk of whiplash in the event of a rear-end collision by supporting the upper body parts and heads of front-seat passengers. And the seatbelt tensioners ensure that passengers remain safely seated during a severe rear-end collision. ISOFIX child-seat anchors are standard for the rear seats and optionally available for the front-passenger seat.
The base version of the updated A4 Sedan has a front surface area of 2.20 m2 (23.68 sq ft). Its coefficient of drag is just 0.27 – a result due in part to the underbody, which is largely covered with plastic panels. The engine compartment has been specifically optimized for low-turbulence flow.
The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.