I don't know if this has been asked for yet, or if this maybe is already possible. What would be great for races like the 24h race at the Nürburgring would be multiple starting groups. They have three different starting groups which do a rolling start with something like 45 seconds distance between the groups. This way we could have massive fields of cars starting, without having problems with performance....because at the start you only have a third of the cars around you. So you could easily also set the visible cars to this third of the overall number of cars. What i am aiming for would be realistic multi class races at the nürburgring with at least 90 participants - 30 per starting group.
