Goals from Yaya Toure, Edin Dzeko and Carlos Tevez at Eastlands continued City's unbeaten start to their title defence.
With Jose Mourinho, manager of City's Champions League opponents Real Madrid, watching from the stands, the hosts did concede an equaliser to Bobby Zamora in the second half, rekindling memories of the last time the clubs faced each other.
Four months on from that last extraordinary meeting between the sides, in which City's 3-2 victory on the concluding day of last season brought them their first English title in 44 years, Mancini's men took the lead after 15 minutes.
Following a prolonged spell of City pressure, David Silva's right-wing corner was met at the far post by Tevez whose first-time volley rebounded against Zamora with the unmarked Yaya Toure handily-place to slot the ball in from 10 yards out.
It was an impressive opening from a City side which did not include any of their five transfer deadline day signings -0 Javi Garcia, Matija Nastasic, Maicon, Scott Sinclair and Richard Wright -- in their starting line-up.
Indeed, City were so dominant QPR's only relief came when another of the home team's recent signings, midfielder Jack Rodwell hit a ridiculous back-pass which almost bounced into his own goal from half-way.
Robert Green subsequently saved well from Silva and the Spanish international forward should have done better when he took Aleksandar Kolarov's superb cross-field pass in his stride but waited to shoot and saw his effort charged down by Fabio da Silva.
The second half opened with Dzeko releasing Tevez who advanced and had a strong shot stopped by the chest of goalkeeper Green at QPR's near post and the relentless waves of Blue pressure continued as Silva cleverly played in over-lapping full-back Pablo Zabaleta whose well-directed shot struck the underside of the crossbar.
City's defensive frailties have been exposed already this season, in conceding four goals in their opening two matches.
So while it was against the run of play, Rangers' equaliser after 58 minutes was not quite as unpredictable a goal as it should have been.
Andrew Johnson dispossessed Silva in midfield and sprinted into the City area where his fierce shot was kept out by the acrobatic dive of Joe Hart, Zamora reacting quickly to stoop and head the rebound into the home goal.
Still, given the manner of City's victory in last season's corresponding fixture, the fact it took Mancini's team just three minutes to regain the lead was no surprise.
Kolarov found the space, and Tevez, in the QPR area, with the forward skilfully taking the ball to the byline where his cross was headed in emphatically by Dzeko.
There was still plenty of City possession before the final whistle, and some anxious moments for home supporters too.
QPR defender Ryan Nelsen twice came close from set-pieces, his bicycle kick flying beyond the far post and then the New Zealand international slid in and almost converted Esteban Granero's free-kick.
But Argentina striker Tevez completed the scoring in the 93rd minute when he deflected Dzeko's wayward strike past the wrong-footed Green.
Source: AFP
Source: AFP