David Silva opened the scoring after 27 minutes with a sumptuous piece of control and half-volley howitzer into the top corner.
He then set up Paco Alcácer just before the break as the reigning European champions erased memories of the shock 3-1 defeat to Slovakia last week. Silva was substituted after 70 minutes - moments after Diego Costa had put La Roja three up and Juan Bernat completed the rout just before full-time.
Meanwhile Joe Hart picked up another clean sheet for his country as England earned a hard-fought 1-0 win in Estonia.
Hart, winning cap No.47, was the only City player to see any action with James Milner an unused sub, but the Estonians failed to muster a shot in anger as England continued their flawless start to the Euro 2016 Qualifiers.
Though the Three Lions dominated the majority of play, it wasn’t until Wayne Rooney’s 73rd minute free-kick that the deadlock was finally broken.
England now lead Group C by three points and are currently nine points ahead of Switzerland who were considered the biggest threat to Roy Hodgson’s side before the qualifiers began.
Stevan Jovetic had a less enjoyable evening as Montenegro were beaten 1-0 by Austria.
Jovetic appeared at half-time for the Montenegrins who already trailed from Okotie’s 23rd-minute goal, but the City striker couldn’t find the equaliser despite a lively cameo role.
Austria now top the group with seven points from nine and Montenegro have four points from three games.
