[Eoussama]

you can make it server sided,

If I were you, I would store vehicle colors into variables
like when you would spray you vehicle, this would happen (vInfo[vehicleid][vColor] = "Black" or vInfo[vehicleid][vColor] = "RED")

then run a repetivive timer, and loop thought every vehicle,

PHP код:

for(new i;i<MAX_VEHICES;i++){
       if(!strcmp(vInfo[vehicleid][vColor], "Black", true)){
              ChangeVehicleColor(i, 0, 0);
       }
       //etc..
}