There have been rumours of unrest in the City camp after another faltering campaign in the UEFA Champions League and some below-par performances in the Premier League.
However, City showed their battling qualities when they came from behind to beat Tottenham 2-1 at the weekend to move into second spot in the table and Hart believes a winning mentality is instilled in their players.
"Our spirit has never been in question," Hart told the Daily Mirror. "We have that and we have quality. Those two combined make us the team we are.
"You have to be able to win when things aren't going your way. That's the only way you're going to win things because people are snapping at your heels, so you have to win regardless of how you play.
"It's not a quality we've developed just recently, it's just instilled in the people.
"We're a group of winners - 20 players who play to win. And we're lucky with that."
Hart believes the comeback victory over Spurs showed why City are the champions.
"Yes, it did, and hopefully we'll be champions again," added Hart
"Someone said before that the quality we've got, on top of our character, means we're going to do well."