The holding midfielder has stated that very few youth players succeed at the Blancos due to the stiff competition for places and the high expectations of the club
The 25-year-old came through the ranks of the club's youth system, but eventually left Los Blancos for Benfica in the summer of 2009, before eventually joining City ahead of the 2012-13 campaign.
"It's hard to get into Madrid and harder still to stay there. It's hard to play in the first team. Only the best make it," Garcia was quoted as saying by AS.
"People now say that the players who left Madrid could have been playing for them, because they ended up with the national team. Maybe, but equally they might have stayed in the club and never progressed as they did
"The best players in the world are there and you have to be tough to cope with the demands of wearing the shirt.
"I wanted to play football, so I left for Benfica and it worked out well for me. Some of the people who have come out of the youth system at Madrid have played for Spain, they've won the World Cup."
Garcia will take on his former team on Wednesday, when City host Madrid at the Etihad Stadium.