Reading showed their pedigree as early as the 10th minute when City skipper Darren Purse missed a tackle out on the right touchline.
The ball was swiftly knocked into the danger area and James Harper was on hand to sweep it into corner of the net for Reading's 100th league and cup goal of the season.
Joe Ledley tried a speculative lob from 30 yards following City's first corner of the match and it had Marcus Hahnemann worried as the ball drifted just over.
Six minutes before the break City fell further behind when their over-worked defence switched off to leave Dave Kitson in front of an open goal and the striker made no mistake.
Another Purse error gifted the Royals a third goal seven minutes after the restart. He missed the opportunity to clear allowing Kitson to run in on goal, but when Neil Alexander blocked his shot, the ball went up in the air and Glenn Loovens headed into his own net.
Dave Jones brought on Paul Parry for Kevin Cooper in the 64th minute and the change paid dividends when Jason Koumas charged down an attempted clearance by Nicky Shorey and crossed to Cameron Jerome who bundled it into the net.
City pulled another back in the 80th minute when Koumas was left free at the near post to head into the corner of the net.
Purse completed a miserable afternoon when his mis-placed pass out of defence was crossed back into the area and Kevin Doyle headed home to restore Reading's two-goal advantage.
Harper crashed in his second and Reading's fifth of the match deep into injury time to end a torrid afternoon for the home defence.