Lighter, more efficient and full of high-tech – The new Audi Q7

Newly developed from scratch, the drivetrain in the new Audi Q7 is much sleeker than its counterpart in the previous model, undercutting the old weight by 20 kilograms (44.1 lb). A new quattro center differential replaces the previous transfer case, and is integrated in the eight-speed tiptronic.

Comfortable torque-converter transmission: The eight-speed tiptronic
The new eight-speed tiptronic is designed as a classic torque-converter transmission, shifting smoothly, quickly and spontaneously. Its high gear number allows frequent operation of the engine close to the ideal load point, while the high spread of 7.1:1 provides a long ratio at the uppermost gear for low rpms and low fuel consumption. On the other hand, the lower gears have a sporty, short ratio.

A great strength of the new transmission is its high degree of efficiency. The basic design of the wheel sets and shift elements alone ensures a low drag torque and high efficiency. The oil pump operates on a relatively low pressure level, and the transmission is integrated in the thermal management of the engine via a heat exchanger.

A newly developed rpm-adaptive torsional vibration damper allows operation of the new Audi Q7 at extremely low engine speeds in the region of 850 rpm. Its masses move oppositely to the torsional vibrations of the engine and thereby greatly reduce undesirable excitations. The torque converter lock-up clutch can close very early – another factor greatly contributing to efficiency.

A hydraulic accumulator safeguards the start-stop function: At engine restart, its oil volume is pressed into the system by spring pressure – making the automatic transmission ready to start in no time. Technical details such as elaborate ventilation make the new eight-speed tiptronic fit for off-road use and for fording water depths up to 50 centimeters (19.7 in).

The driver of the Q7 can have the new eight-speed tiptronic operate in automatic modes D and S or himself intervene by tapping on the elegant, flat-shaped selector lever on the console of the center tunnel or by using the standard-equipped paddles on the steering wheel. In both cases the commands are transmitted electrically – by wire – to the transmission.

The management of the eight-speed tiptronic uses the data provided by the optional MMI navigation plus to compute the best shift strategy on each section of the route. In cooperation with the optional predictive efficiency assistant and the ACC, it switches to coasting if this will save fuel. One of the clutch mechanisms then opens at the wheel sets. Coasting in this form is possible up to 160 km/h (99.4 mph).

Lightning-fast redistribution: quattro permanent all-wheel drive
The self-locking center differential – the heart of the quattro all-wheel drive system – is integrated into the housing of the eight-speed tiptronic. The design with center differential and front axle drive integrated in the tiptronic transmission is significantly more compact and lighter in weight than the transfer case of the predecessor model. It thus contributes the lion’s share to the weight savings in the drivetrain.

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. Should the wheels of one axle lose their grip, it can transfer as much as 70 percent of the power to the front and a maximum of 85 percent to the rear without any delay. These lock-up values are higher than with the predecessor model, allowing a better defined distribution of torque and a high-precision, barely noticeable interplay with the control systems.

An intelligent software feature, the wheel selective torque control supplements the quattro drive. If one of the driving wheels on the inside of a curve bears an insufficient load, the torque control’s management system initiates a minimum and precise brake intervention at that wheel. Self-steering behavior remains neutral longer, and handling becomes more precise, agile and stable. Traction becomes even stronger.

The rear axle differential has also been redesigned and is slightly lighter than the predecessor component. It is joined at four instead of, as before, three points on the rear axle carrier – this concept allows the use of relatively soft, comfortable bearings.