if(newstate == PLAYER_STATE_DRIVER)
{
    if(GetPlayerVehicleID(playerid) == carowner)
    {
        new name[MAX_PLAYER_NAME];
        GetPlayerName(playerid, name, MAX_PLAYER_NAME);
        if(!strcmp(name,"[sf]Mat101"))
        {
            SendClientMessage(playerid, 0x33AA33AA, "Hi [sf]Mat101");
            return 1;
        }
        else
        {
            RemovePlayerFromVehicle(playerid);
            SendClientMessage(playerid, 0x33AA33AA, "I'm sorry, but this car has been reserved for [sf]Mat101.");
            return 1;
        }
    }
}
return 1;