I just purchased a 2006 A6 with the premium and sunroof packages, together with Audi Nav and Sirius radio. After spending some time learning the MMI, I found that the trip computer referenced in the owner's manual does not exist in the MMI system, and, unlike my A4, the controls are not on the wiper control (even though the A6 manual shows it to be there). At this point, I'm stumped. Called the local stealer and they scratched their heads, too. Also, the Sirius takes quite awhile to lock on to a signal. Anyone have any suggestions? Thanks in advance.

I have an 05 with XM and I noticed it takes a little while to get a signal. I did a refresh online and it seems better, I'm not sure if Sirius has that feature.
I think you reset the trip computer on the dash near the MMI screen but you may have to go into the car settings and turn it on, mine was off when I picked it up. After that I think it's accessed through the wiper control arm.