You might be interested in the FAQ that I developed (with many contributors) on AudiWorld for the C4 UrS-cars. Some of you have these cars. Some of the information translates to ABY or ADU powered cars. It's just another resource to check. Don't start any dialogues in the FAQ itself (please and thanks). 
Follow this link (note either scroll down in the page or use "Find in Page" to look for what you need):
http://forums.audiworld.com/s4s6/msgs/149764.phtml
Follow this link (note either scroll down in the page or use "Find in Page" to look for what you need):
http://forums.audiworld.com/s4s6/msgs/149764.phtml