Another thought for skidmarks whilst they're being mentioned: Could we have them persist between races (presumably best handled as a server option). It's purely cosmetic I know, but it makes a big difference IMHO.
On a related note, I've noticed that shift-r on an autocross layout will do a quick spectate and rejoin if there're other cars on track, which leaves skidmarks intact. Shift-r with no cars on track will do a 'proper' restart and remove the skidmarks. Could a restart on an autocross layout do the spec-rejoin regardless of the number of drivers on track as a temporary skidmark-retention measure, if not the above server option?