Audi was already able to reduce the weight of the second-generation TT* thanks to the high aluminum content of the ASF (Audi Space Frame) body. This has been carried over to the third generation of the sports car. The Audi TT 2.0 TFSI with manual transmission and front-wheel drive (excluding driver) weighs just 1,230 kilograms (2,711.7 lb), 50 kilograms (110.2 lb) less than its predecessor. Audi, the leading brand in lightweight construction, has thus once again set a new best mark in this segment.
At Audi, lightweight construction is by no means limited to one specific material. The motto is “The right amount of the right material in the right place for optimal function.” True to this maxim, the new TT features a body in intelligent multimaterial hybrid construction. The front end and floor assembly are made of high-strength and ultra-high-strength steel components, while the superstructure comprises aluminum castings, extruded sections and panels.
The Audi TT uses components of the modular transverse matrix (MQB). At just 2,505 millimeters (8.2 ft), it has the shortest wheelbase in the matrix. The MQB underbody enables the use of many lighter-weight technical components, from the subframes for the front and rear axles to the air conditioner. The new multimaterial hybrid construction lowers the center of mass by ten millimeters (0.4 in), which benefits driving dynamics.
The underbody comprises the longitudinal members, parts of the A-pillars, the bulkhead, the floor, the rear wheel arches and the rear end. At 39.5 kilograms (87.1 lb), hot-formed steels make up roughly a quarter of the weight of overall structure. Before shaping, they are heated to nearly 1,000 degrees Celsius and are then cooled to about 200 degrees in a water-cooled stamping press. This abrupt change in temperature creates an iron-carbon structure with extreme tensile strength. Hot-formed steels are able to perform with relatively thin walls, and this makes them lightweight.
The hot-formed components serve as the backbone of the occupant cell. They are used for the transition zones between the front longitudinal members and the bulkhead, the complete center tunnel, the reinforcing section between the B-pillars and the rear longitudinal members. Ultra-high-strength, cold-formed steel components, extruded aluminum sections for the outer sills and aluminum panels for the rear wheel arches complete the underbody.
The occupant cell superstructure, which at 68 kilograms (149.9 lb) sets a new standard in lightweight construction, is a multi-element aluminum structure. Four castings comprise its nodes. Large nodes at the A-pillars provide the connection between the roof arch, the sills, the windshield cross-member and the upper longitudinal section in the front end. Below the rear window, two smaller cast nodes connect the roof arch with the flat C-pillars and the rear cross-member of the roof. The aluminum section forming the roof arch is produced by hydroforming, in which a straight extruded section is first stretch-bent and then placed into a closed shaping die. There it is brought into its final shape under 2,000 bar of oil pressure and calibrated.
The complete outer skin of the new TT is made of aluminum – the front fenders, the side walls and the roof as well as the hood, doors and rear hatch. The last two components alone save a total of 15.5 kilograms (34.2 lb) over steel. All together, the complete body with all bolt-on parts weighs 276 kilograms (608.5 lb).
Body assembly at the plant in Győr, Hungary, is a high-tech process requiring 3,020 weld points, 1,113 rivets, 44 punch rivets, 128 self-tapping screws, 199 clinch points, 1.9 meters (6.2 ft) of MIG/TMAG welded joints and 4.9 meters (16.1 ft) of laser-welded seams. The bonded seams have a total length of 76 meters (249.3 ft). Robots use hybrid laser welding to produce the seams between the roof and the side panels. The invisible zero-joint on the roof is an expression of Audi’s uncompromising quality philosophy.
No matter what the criterion, composite construction is the ideal concept for the new Audi TT. Static torsional stiffness has been increased by 23 percent compared with the previous model, which was already very stiff. At the same time, the new TT retains its predecessor’s very high dynamic stiffness. The latter is the foundation for the dynamic handling and superior vibrational comfort.
Uncompromising crash safety
The new Audi TT makes no compromises when it comes to crash safety. The hot-formed components form a strong structure of the occupant cell, and the seats can withstand the highest of loads. In a frontal collision, the longitudinal members and the sections in the upper plane absorb a majority of the forces. The bumper cross-members, the rear longitudinal members and the luggage compartment floor work together in the event of a rear-end collision.
In a side-impact collision, the side sills brace against the other vehicle involved in the accident. The solid cross-member section below the rear seat compensates for the lack of a continuous B-pillar. The roof frame offers excellent rollover protection, and pyrotechnic charges blast the hood upward several centimeters in the event of a collision with a pedestrian.
Lowest Cd value in the segment
With a coefficient of drag (Cd) of 0.29 (with the S line exterior package), the new TT has the best value in its segment. Audi has combined the characteristic design with excellent aerodynamics surpassing even the previous model. Lift at the front and rear is very low. At 120 km/h (74.6 mph), a powered spoiler extends from the rear hatch. At 250 km/h (155.3 mph), it generates roughly 50 kilograms (110.2 lb) of downforce on the rear axle. The spoiler retracts again when the speed falls below 70 km/h (43.5 mph).
All exterior details of the new TT and TTS have been precisely tuned to the aerodynamic requirements. The outer vertical struts in the air intakes serve as a pre-spoiler, ensuring that a portion of the slipstream flows cleanly against the flank. A tailored cooling and induction air concept was developed for each engine version. In the TT 2.0 TFSI, for example, the lower zone of the Singleframe is closed. Sealing lips and covers where the air flows in ensure that it is routed to the radiator with virtually zero losses.
A polymer capsule beneath the engine compartment of the TT reduces lift while at the same time improving the flow of air. Below the occupant cell is a large aero-panel, which is supplemented with apertures in the sill region and small spoilers at the fuel tank and in front of the rear wheels.
Made of a lightweight fiber fleece, the aero-panel dampens noise and saves one kilogram (2.2 lb) of weight compared with PP polymer. The foams that block noise in the pillars and sills, the luggage compartment lining and the floor insulation are also very light.
The slim pedestals for the exterior mirrors also have a positive effect on the aeroacoustics. Seals surround the door openings and the doors. A new, additional seal seals the cavity above the hinges of the rear hatch – another key contribution to the low interior noise level. Depending on frequency, Audi has reduced noise by as much as 6 dB versus the previous model.
The equipment, data and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.