if(newstate == PLAYER_STATE_DRIVER) // Means player has got into the drivers seat
{
  if(GetPlayerVehicleID(playerid) == *PUT ID HERE*) // Put the ID (not model) of your admin car here
  {
    if(AdminLevel[playerid] != 1337) //This means if the players admin level is NOT 1337. ie: not admin
    {
      RemovePlayerFromVehicle(playerid); // 0_0
      SendClientMessage(playerid,COLOR_LUL,"Admins Only!"); :D
    }
  }
}