After an early scare which required Aro Muric’s quick movement off his line, City settled into a familiar passing rhythm.
Ian Carlo Poveda and Phil Foden were both denied, by post and goalkeeper respectively, after long, mazy runs through the visitors’ defence.
The opener came in the 20th minute as Foden poked Gonzalez through on goal and the Swiss striker kept his cool in the one-on-one.
It was two just moments later as Newcastle made a number of half-clearances in their own area before Foden fired past them all.
Smith added City’s third on the next attack, creating space for himself on the edge of the box before curling home.
The fourth came just before half-time as Gonzalez drove at the defence, cut on to his left and squeezed his effort inside the near post.
With much of the hard work done and only 40 hours on the clock since the thrashing of Southampton in the FA Youth Cup, City used the second half to make changes including the introduction of fit-again left-back Tyreke Wilson.