Villa have been accused of being too reliant on star striker Christian Benteke and there were question marks raised over how they would cope without the big Belgian during his spell on the sidelines with a hip injury.
However, Villa proved their critics wrong as they battled to a shock 3-2 victory over title hopefuls City at Villa Park and Vlaar feels team spirit was the key to the win.
"We kept on going. The spirit was really good, we put a lot of energy into it and came back two times from a goal behind," said Vlaar.
"It was unbelievable, it was really good.
"Everybody knows how important Christian is for the team. But we showed against Man City we have more to offer and I think we can really be proud of ourselves."
Villa return to action on Saturday when they travel north to face seventh-placed Hull City at the KC Stadium.