The Audi A8 L luxury sedan has a supremely powerful drivetrain. All five engine versions roll off the production line with a new, electronically controlled 8-speed tiptronic automated transmission and quattro permanent all-wheel drive. The dynamic rear axle sport differential is available from Audi as an option, and is standard with the 4.2 TDI quattro.
The eight-speed tiptronic automated transmission has been newly developed from the ground up. Its eight speeds are tightly spaced, yet its high overall gear ratio of 7.0:1 between the shortest and longest gears reduces fuel consumption by about six percent. The A8 L accelerates dynamically when starting off and rolls along highways with low, consumption-reducing engine speeds. All gear changes are fast, very flexible, soft and smooth.
The 8-speed tiptronic is characterized by a high level of efficiency. One of its innovative components is a highly efficient oil pump; another is the heating of the transmission fluid as part of the innovative thermal management to reduce friction losses.
When paired with the 3.0 TDI, it also includes a hydraulic accumulator to provide the start-stop functionality. For the restart, its oil volume is pressed into the system by spring pressure – meaning that the tiptronic is ready to start in no time.
The dynamic shift program (DSP) that controls the eight-speed tiptronic features the automatic operating modes D and S. In a groundbreaking innovation from Audi, it is crosslinked with the detailed route data supplied by the MMI navigation plus system. The DSP uses this data to incorporate upcoming curves into its gearshift strategy – it avoids unnecessary gear changes on narrow roads, for example.
The driver operates the eight-speed tiptronic using the standard shift paddles behind the steering wheel or the elegant selector lever on the center tunnel. The lever is designed to resemble the thrust lever of a yacht and is one of the highlights in the cabin of the large sedan. The lever communicates with the transmission electronically (by wire). Gear changes are triggered by a brief tap of the lever, after which it automatically returns to its center position.
The installation position of the eight-speed tiptronic follows a special layout – as in many models from Audi: The differential is located in front of the torque converter. This moves the front axle a good bit forward, with the advantages being a longer wheelbase, a shorter front overhang and a finely balanced weight distribution. The rear axle differential in the quattro powertrain and the battery in the trunk also factor into this balance.
The quattro permanent all-wheel drive likewise contributes to the leading position of the new A8 L. As with most Audi models, its asymmetric-dynamic configuration provides a sporty characteristic. Its self-locking center differential, a purely mechanical planetary gear, normally sends 60 percent of the torque to the rear axle differential and 40 percent to the front. If one axle slips, the differential transfers a majority of the power to the other axle.
Audi offers the sport differential as an option for customers seeking maximum dynamics. The high-end rear-axle gearbox uses two superposition stages per wheel to steplessly vary the distribution of power between them. The sport differential is standard with the 4.2 TDI quattro. In fast curves, the sport differential literally pushes the large sedan into the radius so that the A8 L corners as if on rails. The system’s controller is integrated into the standard Audi drive select dynamics system; the driver can change between its various characteristics at any time.
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.