I think I suggested it a couple of time now, so I have no hopes of ever seeing it inside lfs...
At first I think that the DC problem is only relevant for endurance racing or races that are above the +1 hour mark and secondly that you'd have to prevent people gaining an advantage from having a sudden timeout and rejoin with a fixed car, new tires and a full tank.
On the other hand it is quite confusing for the driver once he rejoins that he can't tell anymore where he is and which cars he is racing as he'll always get a blue flag when he is near an other car.
I don't know how "easy" it would be to store the car state (fuel, tires, damage) via the server, concidering that in endurance racing not always the driver that timed out will rejoin and continue but his teammate...
An easy start would be to add an admin command like
/addlap <number of laps> <name>
/dellap <number of laps> <name>
which could be used for other stuff as well like penalties.
Just my 2 cents.