I can't speak for Audi, but I had continental tyres on my ford Kuga daily and have to say I was shocked on how fast they did wear out. Got 15k miles out of them in the end. They must be a soft compound. Needless to say I personally won't use continental for this reason.
My A6 used Bridgestone tyres. But cant comment on wear as it's only doing 6k miles a year.