Changing the subject a little bit, as I've played I think I've discovered a potential issue with SR. (Side note: I'm not sure if SR affects your ranking at all, so if it doesn't, please either ignore this or correct me.)
If it's true that ghosting is disabled when you reach class C, then I can see this becoming a vicious cycle due to how sensitive the ghosting system in the E and D classes are. Make one unexpected move and the car ghosts, making it easier to maintain your SR as it significantly reduces the chance of an impact. However, some drivers in E and D classes either aren't good enough to stay out of trouble without ghosting, or intentionally drive in a way that abuses the system. For these guys, they're in for a rude awakening once they get to C class and they find themselves being hit with SR penalties everywhere for actions that were previously OK, which would then demote them back to D class where they can earn that SR back, thus continuing the cycle.