One problem related to ignition has been reported for the 2002 Audi Quattro. The most recently reported issues are listed below.
Electrical system: ignition: coils Audi a630 Quattro 2002 - three coils have failed since January 2002 purchase. Dates are: July 17th, Dec. 4th. , Jan. 7th 2003. Car is dangerous to drive. While driving on highway at 65 mph, car starts to involuntarily slow down and tremble. Have notified dealer and Audi CO. Audi refuses to acknowledge the severity of the problem. In review of this web site's complaints, this is a chronic problem with potential danger to life. Newspapers articles have been written about this. Why isn't Audi responding to consumer complaints - why isn't there a recall?.