I have a SD double bay in the navigation system, ie 2 cards in use. They function reliably, the music is detected quickly and there were never problems. The 16GB are perfect, because you get a lot of music on it, and thus with 2 cards almost always everything thereby.
Using a faster and therefore more expensive card would make only noticeable when copying music to the card. In use in the car it is like saying fast enough. For the Audi MMI Plus therefore an absolute recommendation.
