i once installed it on a audi 200 , it was  wiring ,to switch , speed
sensor, brake and clutch pedals and a vaccume pump . that should cover the
electrical side , on the vaccume side it was, pump to t-peice , pedals, and
linkage to accelerator in the engine bay,  this is just to give you a short
idea of what may be involved , some new audis have a crusie control system
that takes in to account the distance of the car in front ,