I have a 2005 Audi A8 and it is time for the 55,000 mile service. what is required during this service?

On most 55k or 60k services they flush all of the fluids and add new ones. Service the belts if needed. Some dealers even suggest doing the timing belt on them. But to tell you the truth most everything execpt the oil can wait until about 75k. Very little breakdown occurs in the other fluids in this amount of time especially under normal driving conditions. Now if in severe stop and go traffic all the time have the tranny and brake fluid serviced because it will be the worst.

The 55,000 mile service is generally a minor service.
This service generally involves an oil and filter changetire roatation , and a safety inspection. While changing the oil, the mechanic will be performing visual inspections of the brakes, belts, and hoses, inspecting for any fluid leaks, listening for any abnormal noises, and paying attention to any irregularities in the operation of the vehicle.