Well, the subj (German retail version, 4.1.2., stock rooted rom) vs. Audi A8 2010 (MMI 3G+ with online services).
I istalled trial version of the app some time ago but decided to root the phone only today just to try the app. So I deleted the previous connection both from the car and phone and started pairing. Surprisingly it worked - the phone was found as "car phone", contacts were transferred. Car's online services also run - google earth, info from audi connect menu. Phone's apps which require internet connection, got it via wi-fi from the car's router. No 4G supported by the car, of course, but enough speed for Audi music stream phone app with internet radio.
In approx. 10 min. BT connection to the car aborted, had to reestablish it. Then again. The app wrote that trial period was over, maybe this was the problem. Now trying to buy the full app version but cannot do that as the market considers the app incopatible for the phone. Dear admin, is there any solution for the issue?