United needed Antony’s strike and a late Anthony Martial double to save them from a record defeat in the Manchester derby as they remain in sixth, nine points off the top.
Haaland has now scored hat-tricks in each of his last three Premier League home games to take his tally as a City player to 17 in 10 competitive games for the English champions.
“You can see the passes we give each other. We always want to go forward and to attack,” Haaland told Sky Sports.
“It’s what I love about the team. In the end, it’s amazing. There is nothing more to say.”
Since also conceding four times inside the first 45 minutes at Brentford in August, United had bounced back with four consecutive Premier League wins to offer hope they are heading in the right direction under Erik ten Hag.
But the Red Devils were given a rude awakening of the gulf that still exists between the Manchester giants.
“For me it was a surprise. We were not on the front foot, we were not brave on the ball and there were spaces to play but we were not brave enough,” said Ten Hag.
“All the credit to City, but it’s nothing to do with City. Our performance was not good. It had to do with the belief as individuals and as a team.”
City could have scored many more than the four they managed in a blistering first-half performance that swept away any doubts caused by an inconsistent start to the season from Pep Guardiola’s men.
Haaland, Kevin De Bruyne and Bernardo Silva had all seen efforts blocked before Foden opened the floodgates on eight minutes with the Manchester native’s first derby goal.
Ilkay Gundogan’s free-kick hit the post and Foden blasted another big chance wide before Haaland inevitably made his mark on 34 minutes.
Haaland’s hat-trick haul
United were left to bemoan the absence of Raphael Varane to defend a De Bruyne corner as he received treatment on an ankle injury that forced him off before half-time.
Without the Frenchman, there was no match for Haaland’s presence in the penalty box as his header crossed the line before Tyrell Malacia’s attempted clearance.
Moments later, Haaland finished off a slick City counter-attack as Jack Grealish fed De Bruyne, who perfectly picked out the Norwegian to convert on the stretch at the back post.
Haaland then turned provider with a low cross that Foden converted to leave United trailing 4-0 at half-time for the third time in a year.
Unlike in a 5-0 defeat at Old Trafford to Liverpool last season and at Brentford, there was some semblance of a United response after the break.
Antony smashed home his second goal in as many Premier League appearances since a £82 million ($92 million) move from Ajax.
But Haaland quickly reclaimed centre stage with a thumping finish to Sergio Gomez’s cross.
“What Erling is doing, he has done in Norway, Austria, Germany. That is the reality,” said Guardiola.
“So he came and realised my mates run like animals so he has to do it too. And of course the quality we have alongside him helps him to score goals.”
City were on course to match the record margin of victory in a Manchester derby when Haaland set up Foden to smash home and complete his hat-trick.
That was Foden’s final involvement as he was withdrawn in a quadruple change as Guardiola could afford to also hand a rest to De Bruyne, Gundogan and Grealish.
United took advantage of City taking their foot off the accelerator in the final 10 minutes as substitute Martial scored twice to cut the arrears.
The Frenchman headed in the rebound after Ederson parried Fred’s shot and then emphatically fired home from the penalty spot.
In contrast to the goalfest at the Etihad, it was scoreless at Elland Road where Leeds and Aston Villa played out a 0-0 draw.
Leeds were reduced to 10 men early in the second half when Luis Sinisterra was shown a second yellow card, but Villa failed to make the man advantage count to keep the pressure on manager Steven Gerrard.