[MA_proking]

Just put this under onplayercommand after {(bracket) in you gm

Code:

 if(strcmp(cmdtext, "/flip", true) == 0)
  {
  if(IsPlayerInAnyVehicle(playerid))
  {
    new currentveh;
    new Float:angle;
    currentveh = GetPlayerVehicleID(playerid);
    GetVehicleZAngle(currentveh, angle);
    SetVehicleZAngle(currentveh, angle);
    SendClientMessage(playerid, 0xFFFFFFFF, "Your vehicle has been flipped.");
    return 1;
  }
  else
  {
    SendClientMessage(playerid, 0xFFFFFFFF, "You are not in any vehicle!");
    return 1;
  }
  }