And when was the least time this happened in the English top flight?
Well, there's still over half a season to go, and anything can happen as we approach the end. If they somehow retain participation in CL and FA cup by January, then we can look to factor in fatigue. Then again, they have a LOT of depth
My personal guess? We'll see them lose with months left to spare, even if it does look like they'll get the title this year.
Last time this happened? Arsene Wenger's Invincibles more than a decade ago. I remember it well. Those were the days we still had tough tacking midfielders, no nonsense centre backs and proper strikers/centre forwards! I also remember very, very well the match that ended their 49-game unbeaten streak (12 draws)... that crazy fiery game with Man Utd. Ah, those days of spirit and fire and rivalry! They were eliminated from cup games towards the end, so that helped a lot.
Odds for Man City to remain unbeaten in EPL all season: 7/1.