Though City appear likely to relinquish their title to local rivals United, who are 15 points clear at the top, the reigning champions want to finish the season with a flourish and proved too strong for Newcastle once Carlos Tevez had made the breakthrough on 41 minutes.
David Silva added another before the interval and further goals from returning captain Vincent Kompany and a James Perch own goal after he deflected Yaya Toure's cross were just reward for City's dominance.
The first half had reached the midway point before anything noteworthy happened when a rare foray forward by Newcastle ended with Papiss Cisse striking the post from a narrow angle following a fine pass by Vurnon Anita.
City responded immediately and should have taken the lead, only for Gareth Barry to side-foot over from close range after Edin Dzeko's shot had been blocked by Newcastle keeper Rob Elliot.
The hosts were in control of the game and Gael Clichy's well-struck effort was beaten out by Elliot, who was spoken to by referee Neil Swarbrick on 36 minutes for timewasting.
Tevez and Barry combined well on the edge of the box to play in Silva on 38 minutes, but he swept home from an offside position before City deservedly went ahead four minutes before half-time.
Silva was in the thick of things again as he released Clichy on the left and the full-back's teasing low cross was forced home at the far post by Tevez.
Elliot then produced a superb fingertip save to deny Dzeko, but the Newcastle keeper was beaten again in stoppage-time by Silva's drilled shot following a jinking run by Samir Nasri.
Newcastle returned for the second half with a much more positive approach and were almost rewarded within three minutes after Yohan Cabaye flashed a shot wide following a clever pass by Moussa Sissoko.
The Magpies' momentum was checked, though, on 56 minutes by a third City goal as Kompany's flick, from Barry's deflected shot, nicked Danny Simpson on its way past a helpless Elliot.
Things got worse for Newcastle on 69 minutes when Toure muscled his way into the box, and his attempted cross deflected off half-time substitute James Perch and flew beyond Elliot.
City keeper Joe Hart made a comfortable low save from Dan Gosling before his opposite number Elliot produced a flying stop to deny substitute Scott Sinclair as the home side tightened their grip on second spot with the minimum of fuss.