Victory over the Black Cats extends City's 100% start to the Premier League season as Maresca's charges now open up a three-point lead over Arsenal after five games played.
Two goals from Antoine Semenyo - plus efforts from Erling Haaland, Rayan Cherki and a club first for Enzo Fernandez - secured the win despite conceding a hat-trick from Brian Brobbey.
Maresca was breathless at full-time and admitted the excitement might have been a bit too much for him at the Etihad Stadium.
"There were too many goals, I prefer 1-0," he joked with Sky Sports after the game.
"Overall, I'm happy for result, but also for the performance of the players.
"However, the way we conceded the goals against was not good. Two of them were too easy. The second goal came from Granit Xhaka's quick free-kick and that cannot happen.
"The third goal came from another free-kick. It was too easy, we conceded more chances, but we also scored five and could have scored probably two or three more."