From the GT Sport website.
http://www.gran-turismo.com/us/products/gtsport/driving/
http://www.gran-turismo.com/us/products/gtsport/sport_mode/
From Kaz himself
http://www.eurogamer.net/articles/2016-05-25-gran-turismo-sport-is-a-fascinating-antiquity
iRacing doesn't have a driver preparation system other than videos and telling you to read the sporting code, also iRacing is very difficult to find the limited and poorly organised information that it does provide compared to an easy to use GT menu and progression system, that is why we have a need for sites like edracing. So what we know about GTS is already superior in this regard.
As far as matchmaking goes I didn't say it was superior, I said I have my fingers crossed from what I have read that it will be superior. Not that it will be hard to be better than iRacings match making system as it is very flawed as argued over in many threads on iRacing and even Tony Gardner has said that he would like to implement suggestions that have been made in the forum but it is not a priority for them at this stage.
But just based on the above we can see that Sportsmanship Rating or SR
will actually form part of the matchmaking process which is immediately a step up from iRacings matchmaking in my opinion. Of course we see no other mention of something similar to iRating and from what we can read it would seem that they have the crazy idea of only using SR as a splitting system but common sense says surely this isn't the case so for now I will imagine that PD are not insane and there will be a combined approach using both SR and a driver rating system that takes performance into account for splitting. Or perhaps they will be true to real life and actually use qualifying, imagine that
So if GT was my baby this is how I would do it. Certain parts of the offline campaign would form part of the Sportsmanship Rating and the less of it you have done the lower your SR will be when you begin online racing. From that point SR would divide drivers into bands and you would only be matched against people in your bands. Then within the bands I would use either qualifying or a performance rating system like IR to split people. Either way for the point of driver scoring for championship purposes I would take a page out of the leagues book and the score would be first based on finishing position but then reduced by incidents in the race. Likewise if I had a driver rating like IR it would also be adjusted by incidents. Because I am sure that GT will not have a strong collision or damage model I think this approach is required to ensure high driving standards and prevent bump and run type passing. As long as the penalty for a contact is greater than the gain for the extra position most people will generally try and avoid the bump and run tactic.
With such systems I do feel that the driver rating system would then be better than qualifying to split people within their own bands because even though qualifying is more realistic to what we see in real life in real life we do not see a single race split into 50 individual races and using qualifying times for this purpose could see top drivers not make the top race. But a driver rating system would be based on consistent performance and that would put the top drivers where they belong eventually.
For now what we know about GTS is it will have a splitting system that takes into account SR for the purpose of matchmaking and we know it will also be a serious esports entry with a global competition with serious prizes so they will also need systems in place to make sure that drivers are ranked based on their performance and that the correct drivers do progress to race each other in finals. And that logic is what gives me some faith that SR is not the only factor that determines splits because as much as people should be matched against others based on their sportsmanship levels they also need to be challenged for racing to be fun and anyone can stay out of trouble if they are put into races that present them with no real competition and they can simply stay out in front away from danger.