Hart, currently preparing for England's World Cup qualifiers with San Marino and Montenegro, has seen the Red Devils open up a 15-point lead with just eight games remaining.
The goalkeeper concedes City have been "disappointing" in their defence of the title - although he refuses to throw in the towel - and some of his own performances have been criticised by Roberto Mancini.
But Hart also gives credit to the way the Red Devils have swept aside all challengers to put them on the verge of another championship.
When asked why City have not been at their best, Hart said: "I don't know, I'd love to know. It would have been rectified.
"Maybe we have drawn more games than we would have liked to but it has not been a perfect season - and it needs to be pretty perfect to win this league.
"We have done well but we have been up against a killing machine that have kept turning out results no matter what.
"It is a tough league, it's hard to win games. Unfortunately when we do lose, United stretch that lead and it has been disappointing but we will keep going.
"We worked so hard to get that title we are never going to just give it away. I'd imagine from the outside it looks that way, but that's just not the case."
Regarding Mancini's criticism of himself, Hart said: "You have got to be able to move on. Everyone is going to have their opinion.
"What is said in private, that's for behind the scenes but he (Mancini) is free to do his press conferences as he feels and if he feels you are not up to it ..."
When suggested Sir Alex Ferguson would not criticise his players publicly, Hart said: "All managers have their different way of doing things."
Hart accepts everyone is entitled to praise or criticise him if his standards drop.
"I've tried to stay consistent, prepare and show desire in the games.
"I do everything I can to stop goals; sometimes I can save it, sometimes not. Sometimes the ones that I should be saving, haven't been saved.
"But as long as I've kept my prime focus of doing everything I can, then that's all I can really do.
"Am I a victim of standards? I'm definitely not a victim. I love playing, I love training hard, I love playing hard and I love winning.
"I have to accept when I'm playing that there's going to be another side and you have to take that sometimes.
"People are free to criticise or praise. I'm never going to tell anyone what to say or do about me but at the same time I don't have to listen.
"I'm pretty strong with how I feel about what I should and shouldn't have done.
"That's the beauty of football and that's why it's such a big industry and that's why it gets so many people involved. People are allowed their opinions."
Hart insists there is a good relationship amongst the City and United players when on England duty despite their intense rivalry at club level.
He said: "Do I talk to the United players? Of course, you have got to be able to. It's not personal.
"It's definitely not a personal thing. What they are doing is exactly what I want to be doing right now this year.
"It was vice versa last year. That's just how it is and the same with the Chelsea boys, the same with the Tottenham boys. We are all fighting for something with England.
"We are not fighting each other. We are fighting for our teams and our clubs and you have to be selfish in those terms.
"When you come away with England it has gone, we are playing for England and we are fighting for England, that is what we move forward with."
@crookster Spot on mate, took the words out of my mouth. beaver69 made a valid point criticising his own team and being humble, and all solskjaer 99 could do was try and pick a fight. That's what gives us fans a bad name.- fc_manc