Audi A6
Audi made a high-performance, 4.2-litre V8 engine (parts code prefix: 077, identification code: AEC) with a Bosch KE-Motronic ECU available as an option in the original European S4s, and made the decision to continue to do so with the S6, making a version of the 4.2 available as an optional upgrade over the 2.2-litre inline five-cylinder turbo. Unlike the five-cylinder turbocharged version, the V8-powered S6 was supplied with a four-speed automatic transmission as standard, but kept the quattro four wheel drive. A six-speed manual gearbox was also available as an option.
Audi A8
A sports-optimised ZF "6HP26-A61" six-speed tiptronic automatic transmission with "Dynamic Shift Programme" (DSP) and "sport" mode, with steering wheel mounted paddle-shifters, is the only offering. Output is transmitted via Audi's quattro generation IV all-wheel drive system, initially using the Torsen T-2 50:50 dynamic centre differential, and from 2007 for the 2008 model year, utilising the Torsen T-3 asymmetric dynamic centre differential, with a "default" torque distribution of 40 percent to the front axle and 60 percent to the rear. If the road conditions change, the purely mechanical differential responds without any delay; it can divert up to 85 percent of power to the rear wheels, and as much as 65 percent to the front wheels.