public OnPlayerStateChange ( playerid, newstate, oldstate )
{
    switch ( newstate )
    {
        case PLAYER_STATE_DRIVER, PLAYER_STATE_PASSENGER:
            PlayAudioStreamForPlayer ( playerid, "URL-RADIO" );
    }
    switch ( oldstate )
    {
        case PLAYER_STATE_DRIVER, PLAYER_STATE_PASSENGER:
            StopAudioStreamForPlayer ( playerid );
    }
    return 1;
}