With respect to road behavior, the Audi SQ7 TDI combines numerous talents, from highly comfortable cruising on the highway to dynamic handling on a mountain road. The compact and lightweight self-locking center differential is the heart of the quattro permanent all-wheel drive system, which is purely mechanical. Under normal driving conditions, the center differential, designed as a planetary drive, distributes the power between the front and rear axles in a 40:60 ratio. If a wheel on one of the axles slips, e.g. when on a slippery surface, the self-locking differential immediately directs the majority of the power to the axle with the better traction. If necessary, up to 85 percent of the drive torque can be directed to the rear axle or up to 70 percent to the front axle.
The chassis adheres to the principle of strict lightweight construction. Its five-link suspensions front and rear are made largely of aluminum. Electromechanical power steering, the Audi drive select dynamic handling system and the adaptive air suspension with S-specific tuning are standard.
The SQ7 TDI rolls standard on 20-inch wheels with size 285/45 tires. Alternatives range up to 22-inch tires from the Audi sport line from quattro GmbH. The brakes are big and powerful. Mounted on the front axle are internally ventilated, lightweight discs measuring 400 millimeters (15.7 in) in diameter. They are gripped by black (optionally red), six-piston calipers with S logos. A brake system with particularly lightweight and abrasion-resistant carbon fiber-ceramic disks will follow shortly after the market launch.
Innovative technology modules: the driving dynamics package
Upon request, Audi will equip the SQ7 TDI with a driving dynamics package comprising three technology modules: the sport differential, all-wheel steering and electromechanical active roll stabilization.
During sporty cornering, the sport differential ensures that steering commands are carried out precisely and stably. The superior control is achieved by means of a variable torque between the wheels of the rear axle.
A software function continuously computes the ideal distribution with respect to handling. When turning into or accelerating in a curve, the majority of the torque is directed to the outside wheel, pushing the car into the curve. Before the rear end can break out, the vehicle is stabilized and thus easily controlled.
Another optional system for the new Audi SQ7 TDI is all-wheel steering. Installed at the rear axle is a steering system with electrical spindle drive and two track rods that turns the rear wheels a few degrees in the same or opposite direction relative to the front wheels, depending on the situation. At low speeds, the rear wheels turn in the opposite direction. The large SUV thus becomes significantly even more agile, and its turning radius smaller by up to one meter (3.3 ft) – as noticed quite clearly by the driver during maneuvering and parking. At slow speeds between five and 15 km/h (3.1 - 9.3 mph), the oppositely directed steering can range up to five degrees. At higher speeds the rear wheels follow the movement of the front wheels up to an angle of 3.5 degrees. Turning in the same direction improves the steering response and further increases stability in evasive maneuvers.
The third component is the electromechanical active roll stabilization, another innovation from Audi. With this system, a compact electric motor at the front and the rear axle with a three-stage planetary gearbox separates the two halves of the stabilizer. On an uneven road surface, they are decoupled from one another, which improves ride comfort. During sporty driving, the tubes are actively twisted against each other. That significantly reduces body roll, i.e. the lean of the car. Together with the planetary gear, an electric motor produces anything up to 1,200 Nm (885.1 lb-ft) of torque.
The effect is taut, sporty handling: The car leans less in bends, and the tendency to understeer is further reduced. This enables higher lateral acceleration and thus faster cornering. The front and rear stabilizer can be adjusted independently of each other. This active distribution of power between the front and rear axles significantly enhances steering precision and the agility of the automobile.
Like the electric powered compressor, the electromechanical active roll stabilization draws its drive power from the new 48 volt electrical subsystem, making it more powerful and faster than a conventional hydraulic system. The new electromechanical active roll stabilization technology from Audi can also recuperate. If the wheels on one axle are deflected to greatly differing extents on bumps in the road, they excite the stabilizer – the electromechanical active roll stabilization motor now converts each impulse into electrical energy. This energy is stored in the 48 volt electrical subsystem’s lithium-ion battery, ensuring that the overall energy balance of the electromechanical active roll stabilization is significantly more favorable than that of a hydraulic system. Because it requires no oil, the electromechanical active roll stabilization is also maintenance-free and environmentally friendly.
Dynamic control: the electronic chassis platform
The adaptive air suspension and now for the first time also the electromechanical active roll stabilization and sport differential are connected to the central control unit called the electronic chassis platform. This is highly precise and adapts to the situation at hand. Computation and adjustment of the handling functions take place in a one-millisecond cycle. By comparison: A blink takes roughly 100 times as long. The electronic chassis platform sends the computed values for the mechanical adjustment to the roll stabilization and/or to the sport differential and adjusts the air suspension setting.
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.