[Ash.]

pawn Код:

stock IsVehicleOccupied(vehicleid)
{
    for(new i; i < GetMaxPlayers(); i++)
    {
        if(IsPlayerConnected(i)) continue;
        if(GetPlayerVehicleID(i) == vehicleid) return 1;
    }
    return 0;
}

CMD:respawnvehicles(playerid, params[])
{
    #pragma unused params
    for(new i; i < MAX_VEHICLES; i++) if(!IsVehicleOccupied(i)) SetVehicleToRespawn(i);
    return 1;
}

Had this lying around. Hope it helps!