The Premier League’s bottom side failed to rouse themselves for a must-win game at the Etihad Stadium and seemed doomed after conceding Aguero’s first after just four minutes.
Aleksandar Kolarov, James Milner and David Silva also got on the scoresheet as rampant City, who hit the woodwork as well through Wilfried Bony, kept up their challenge for second place with a fourth successive win.
But the story of the afternoon was QPR’s sorry demise after just one season back in the top flight.
Questions will now be asked about the future of manager Chris Ramsey and, perhaps more seriously, the status of the club itself with the Football League’s position over their financial situation still unclear.
While City’s biggest problem on the day was how to get fit-again Yaya Toure and Vincent Kompany back into the team — both were on the bench — QPR’s sorry day began with administrative issues.
It emerged prior to the game that midfielder Sandro had been withdrawn on Home Office advice because of an issue relating to his UK residency visa.
Clint Hill, Steven Caulker and Bobby Zamora did at least pass fitness tests but once the game began, it seemed the visitors lacked heart for the battle.
Results on Saturday had sent the Londoners to the bottom of the table, needing to win to have any hope of survival, but their body language never seemed right.
Strikers Zamora and Charlie Austin did look like they could trouble City but the team’s general lack of bite meant they were fighting a lost cause.
The writing seemed on the wall in the opening minutes when Leroy Fer gave the ball away and Silva charged through a gap to release Aguero.
The Argentinian’s effort was blocked on this occasion but he made no mistake in the fourth minute when he burst through some poor tackling.
He did get a lucky rebound off Matt Phillips but his finish from close range was clinical as he dinked over Rob Green.
Austin did rattle the crossbar and power a header past Joe Hart as the hosts twice switched off at the back, but the flag was up on both occasions.
City doubled their lead when dead-ball specialist Kolarov clipped a free-kick over the wall and beyond Green. Aguero almost added another but Green came out to block.
City extended their lead after a Yun Suk-young blunder early in the second half. The Korean failed to make a routine interception as Silva sent a long ball forward and Aguero was quick to pounce, racing through and giving Green no chance.
Aguero completed his hat-trick from the spot after Silva was bundled over byPhillips.
Milner tapped in the fifth and Silva completed the humiliation four minutes from time when he took Bony’s backheel in his stride and calmly went round Green.
Afterwards, Ramsey strongly reiterated his desire to remain as QPR manager and start the rebuilding process. “It’s a club that I’ve taken to my heart and I really want to be here,” he said.
“On the day we didn’t really turn up and they’re a very good team.
“Man for man throughout the pitch today the boys will have been very disappointed with the way they’ve performed.
“We really feel sorry for the family of fans that came here today that we’ve put out that level of performance.”
It was a chastening way to have relegation confirmed, with QPR now propping up the table an unassailable nine points off safety with just two games left.
Hart, Zabaleta, Demichelis, Mangala, Kolarov, Fernando, Fernandinho (Toure 75), Milner (Jesus Navas 82), Lampard (Bony 63), Silva, Aguero.
Green, Caulker, Dunne, Hill, Phillips, Henry, Barton, Yun (Wright-Phillips 86), Fer (Kranjcar 78), Austin, Zamora (Hoilett 53).