The Portuguese mentor highlighted the impact the Betway Premiership champions had had at the tournament in the USA – being admired by fans and pundits alike for their display against Ulsan, Borussia Dortmund and Fluminense in Group F.
Cardoso said they were not outplayed at all, even though they missed out on the knockout stages and are now headed back home.
"I think it's very easy to speak about matches like this, despite the emotions that might be inside of us and of me, but I think it's easy because everybody had a chance to watch a wonderful football match," said Cardoso.
"Everybody had a chance to watch 22 players playing at the highest level, in not the easiest conditions, but why it makes it so easy for me is to understand the level at which my players played – that is something absolutely marvellous to see.
"I think, and I'm speaking probably to the ones who are less [accustomed to] international football, I invite them to go and study a little bit the teams of Fluminense, Borussia Dortmund, and even Ulsan, to understand the level at which Sundowns played at this Club World Cup."
Cardoso noted how his charges were getting compliments from rival coaches during the tournament.
"I don't speak only for myself, I heard the coaches speaking from the other teams and I know what they told me, when I hear them saying, 'Respect for you. Respect for what you did, you were better than us,'" he shared.
"That doesn't fulfil our objectives but it makes us much better than we were when we arrived here, and there are teams that come to the Club World Cup and leave without taking anything.
"But Mamelodi Sundowns leaves the competition having taken a lot of things – we made four points, and we lost one out of three matches, but the character we showed in these three matches is absolutely outstanding."