This is going to be a very interesting car to watch in the next 3 years or so, for various reasons.
First, as an owner of Audi A6 (C6) 3.0T in US, this S9 Max/Ultra introduction is going to attack the 78S segment with 56E pricing. From my own personal perspective, I would take S9 over a new A6 3.0T in a heartbeat (their out-of-door costs should be very comparable).
Second, owners in the 78S segment are very different from the owners of AITO M9. They are mainly older conservative male with high consciousness of self image. For the time being, I think S9 can steal some 56E customers. But It would be a surprise to me if S9 can sell over half of what M9 sells on monthly basis going forward.
In the last 3 decades, only Lexus LS400 (and later) and Audi A8 has established credible competition to Benz S500 and BMW 7i. If S9 could reach to comparable monthly sales of 78S in China in the next 2 years or so, I would consider that as a historical event in luxury car history.
