[Kayaque]

I believe this is exactly what you're looking for.

pawn Код:

stock IsVehicleEmpty( vehicleid )
{
    for ( new playerid = 0; playerid < MAX_PLAYERS; playerid++ )
    {
        if ( !IsPlayerConnected( playerid ) )
            continue;

        if ( GetPlayerVehicleID( playerid ) == vehicleid )
            return false;
    }

    return true;
}

A rep+ would be appriciated.