This is a complex car. The combustion chambers have five valves (three intake), and timing is adjustable on both camshafts (the timing belt drives the water pump). Brake assist increases brake boost when the control unit senses the driver is making a panic stop, and self-leveling headlights are available. The A6 is the largest car available with a Continuously Variable Transmission (CVT).
Filling or checking the fluid level on either transmission requires a lift and special tools, including a scan tool.
The fluids are highly specialized, particularly for the CVT, and the OE fluid is strongly recommended. The 5-speed uses part number G 052 162 A2, while the CVT uses part number G 052 190 A2. Audi coolant is G12 (red).
The front suspension uses two upper and two lower ball joints on each side, and Audi provides no caster alignment specifications.
Service bulletins were issued to address low engine oil pressure, a variety of transmission problems (both 5-speed and CVT), MIL illumination with camshaft and/or misfire codes, coolant leaks and unnecessary ABS actuation. One TSB describes a software quirk that causes the PCM to become confused when the brake and accelerator are pressed at the same time.